diff --git a/NOTICES.txt b/NOTICES.txt
index cdd00a5ec..63039c3e3 100644
--- a/NOTICES.txt
+++ b/NOTICES.txt
@@ -31,6 +31,16 @@ It also uses derivations of SwiftNIO's lock 'NIOLock.swift' and locked value box
 
 ---
 
+This product uses derivations of SwiftNIOHTTP2's implementation of case
+insensitive comparison of strings, found in 'HPACKHeader.swift'.
+    
+    * LICENSE (Apache License 2.0):
+      * https://github.com/apple/swift-nio-http2/blob/main/LICENSE.txt
+    * HOMEPAGE:
+      * https://github.com/apple/swift-nio-http2
+
+---
+
 This product contains a derivation of the backpressure aware async stream from
 the Swift project.
 
@@ -38,3 +48,12 @@ the Swift project.
     * https://github.com/apple/swift/blob/main/LICENSE.txt
   * HOMEPAGE:
     * https://github.com/apple/swift
+
+---
+
+This product uses derivations of swift-extras/swift-extras-base64 'Base64.swift'.
+
+  * LICENSE (Apache License 2.0):
+    * https://github.com/swift-extras/swift-extras-base64/blob/main/LICENSE
+  * HOMEPAGE:
+    * https://github.com/swift-extras/swift-extras-base64
diff --git a/Sources/GRPCCore/Internal/Base64.swift b/Sources/GRPCCore/Internal/Base64.swift
new file mode 100644
index 000000000..6265b996b
--- /dev/null
+++ b/Sources/GRPCCore/Internal/Base64.swift
@@ -0,0 +1,605 @@
+/*
+ * Copyright 2023, gRPC Authors All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+// This base64 implementation is heavily inspired by:
+
+// https://github.com/lemire/fastbase64/blob/master/src/chromiumbase64.c
+/*
+ Copyright (c) 2015-2016, Wojciech Muła, Alfred Klomp,  Daniel Lemire
+ (Unless otherwise stated in the source code)
+ All rights reserved.
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are
+ met:
+
+ 1. Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+ 2. Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in the
+    documentation and/or other materials provided with the distribution.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+ TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+// https://github.com/client9/stringencoders/blob/master/src/modp_b64.c
+/*
+ The MIT License (MIT)
+
+ Copyright (c) 2016 Nick Galbreath
+
+ Permission is hereby granted, free of charge, to any person obtaining a copy
+ of this software and associated documentation files (the "Software"), to deal
+ in the Software without restriction, including without limitation the rights
+ to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ copies of the Software, and to permit persons to whom the Software is
+ furnished to do so, subject to the following conditions:
+
+ The above copyright notice and this permission notice shall be included in all
+ copies or substantial portions of the Software.
+
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ SOFTWARE.
+ */
+
+internal enum Base64 {}
+
+extension Base64 {
+  internal struct DecodingOptions: OptionSet {
+    internal let rawValue: UInt
+    internal init(rawValue: UInt) { self.rawValue = rawValue }
+
+    internal static let base64UrlAlphabet = DecodingOptions(rawValue: UInt(1 << 0))
+    internal static let omitPaddingCharacter = DecodingOptions(rawValue: UInt(1 << 1))
+  }
+
+  internal enum DecodingError: Error, Equatable {
+    case invalidLength
+    case invalidCharacter(UInt8)
+    case unexpectedPaddingCharacter
+    case unexpectedEnd
+  }
+
+  internal static func decode(
+    string encoded: String,
+    options: DecodingOptions = []
+  ) throws -> [UInt8] {
+    let decoded = try encoded.utf8.withContiguousStorageIfAvailable {
+      (characterPointer) -> [UInt8] in
+      guard characterPointer.count > 0 else {
+        return []
+      }
+
+      let outputLength = ((characterPointer.count + 3) / 4) * 3
+
+      return try characterPointer.withMemoryRebound(to: UInt8.self) { (input) -> [UInt8] in
+        try [UInt8](unsafeUninitializedCapacity: outputLength) { output, length in
+          try Self._decodeChromium(from: input, into: output, length: &length, options: options)
+        }
+      }
+    }
+
+    if decoded != nil {
+      return decoded!
+    }
+
+    var encoded = encoded
+    encoded.makeContiguousUTF8()
+    return try Self.decode(string: encoded, options: options)
+  }
+
+  private static func _decodeChromium(
+    from inBuffer: UnsafeBufferPointer<UInt8>,
+    into outBuffer: UnsafeMutableBufferPointer<UInt8>,
+    length: inout Int,
+    options: DecodingOptions = []
+  ) throws {
+    let remaining = inBuffer.count % 4
+    switch (options.contains(.omitPaddingCharacter), remaining) {
+    case (false, 1...):
+      throw DecodingError.invalidLength
+    case (true, 1):
+      throw DecodingError.invalidLength
+    default:
+      // everythin alright so far
+      break
+    }
+
+    let outputLength = ((inBuffer.count + 3) / 4) * 3
+    let fullchunks = remaining == 0 ? inBuffer.count / 4 - 1 : inBuffer.count / 4
+    guard outBuffer.count >= outputLength else {
+      preconditionFailure("Expected the out buffer to be at least as long as outputLength")
+    }
+
+    try Self.withUnsafeDecodingTablesAsBufferPointers(options: options) { d0, d1, d2, d3 in
+      var outIndex = 0
+      if fullchunks > 0 {
+        for chunk in 0 ..< fullchunks {
+          let inIndex = chunk * 4
+          let a0 = inBuffer[inIndex]
+          let a1 = inBuffer[inIndex + 1]
+          let a2 = inBuffer[inIndex + 2]
+          let a3 = inBuffer[inIndex + 3]
+          var x: UInt32 = d0[Int(a0)] | d1[Int(a1)] | d2[Int(a2)] | d3[Int(a3)]
+
+          if x >= Self.badCharacter {
+            // TODO: Inspect characters here better
+            throw DecodingError.invalidCharacter(inBuffer[inIndex])
+          }
+
+          withUnsafePointer(to: &x) { ptr in
+            ptr.withMemoryRebound(to: UInt8.self, capacity: 4) { newPtr in
+              outBuffer[outIndex] = newPtr[0]
+              outBuffer[outIndex + 1] = newPtr[1]
+              outBuffer[outIndex + 2] = newPtr[2]
+              outIndex += 3
+            }
+          }
+        }
+      }
+
+      // inIndex is the first index in the last chunk
+      let inIndex = fullchunks * 4
+      let a0 = inBuffer[inIndex]
+      let a1 = inBuffer[inIndex + 1]
+      var a2: UInt8?
+      var a3: UInt8?
+      if inIndex + 2 < inBuffer.count, inBuffer[inIndex + 2] != Self.encodePaddingCharacter {
+        a2 = inBuffer[inIndex + 2]
+      }
+      if inIndex + 3 < inBuffer.count, inBuffer[inIndex + 3] != Self.encodePaddingCharacter {
+        a3 = inBuffer[inIndex + 3]
+      }
+
+      var x: UInt32 = d0[Int(a0)] | d1[Int(a1)] | d2[Int(a2 ?? 65)] | d3[Int(a3 ?? 65)]
+      if x >= Self.badCharacter {
+        // TODO: Inspect characters here better
+        throw DecodingError.invalidCharacter(inBuffer[inIndex])
+      }
+
+      withUnsafePointer(to: &x) { ptr in
+        ptr.withMemoryRebound(to: UInt8.self, capacity: 4) { newPtr in
+          outBuffer[outIndex] = newPtr[0]
+          outIndex += 1
+          if a2 != nil {
+            outBuffer[outIndex] = newPtr[1]
+            outIndex += 1
+          }
+          if a3 != nil {
+            outBuffer[outIndex] = newPtr[2]
+            outIndex += 1
+          }
+        }
+      }
+
+      length = outIndex
+    }
+  }
+
+  static func withUnsafeDecodingTablesAsBufferPointers<R>(
+    options: Base64.DecodingOptions,
+    _ body: (
+      UnsafeBufferPointer<UInt32>, UnsafeBufferPointer<UInt32>, UnsafeBufferPointer<UInt32>,
+      UnsafeBufferPointer<UInt32>
+    ) throws -> R
+  ) rethrows -> R {
+    let decoding0 = options.contains(.base64UrlAlphabet) ? Self.decoding0url : Self.decoding0
+    let decoding1 = options.contains(.base64UrlAlphabet) ? Self.decoding1url : Self.decoding1
+    let decoding2 = options.contains(.base64UrlAlphabet) ? Self.decoding2url : Self.decoding2
+    let decoding3 = options.contains(.base64UrlAlphabet) ? Self.decoding3url : Self.decoding3
+
+    assert(decoding0.count == 256)
+    assert(decoding1.count == 256)
+    assert(decoding2.count == 256)
+    assert(decoding3.count == 256)
+
+    return try decoding0.withUnsafeBufferPointer { (d0) -> R in
+      try decoding1.withUnsafeBufferPointer { (d1) -> R in
+        try decoding2.withUnsafeBufferPointer { (d2) -> R in
+          try decoding3.withUnsafeBufferPointer { (d3) -> R in
+            try body(d0, d1, d2, d3)
+          }
+        }
+      }
+    }
+  }
+
+  internal static let encodePaddingCharacter: UInt8 = 61
+  static let badCharacter: UInt32 = 0x01FF_FFFF
+
+  static let decoding0: [UInt32] = [
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x0000_00F8, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0000_00FC,
+    0x0000_00D0, 0x0000_00D4, 0x0000_00D8, 0x0000_00DC, 0x0000_00E0, 0x0000_00E4,
+    0x0000_00E8, 0x0000_00EC, 0x0000_00F0, 0x0000_00F4, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0000_0000,
+    0x0000_0004, 0x0000_0008, 0x0000_000C, 0x0000_0010, 0x0000_0014, 0x0000_0018,
+    0x0000_001C, 0x0000_0020, 0x0000_0024, 0x0000_0028, 0x0000_002C, 0x0000_0030,
+    0x0000_0034, 0x0000_0038, 0x0000_003C, 0x0000_0040, 0x0000_0044, 0x0000_0048,
+    0x0000_004C, 0x0000_0050, 0x0000_0054, 0x0000_0058, 0x0000_005C, 0x0000_0060,
+    0x0000_0064, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x0000_0068, 0x0000_006C, 0x0000_0070, 0x0000_0074, 0x0000_0078,
+    0x0000_007C, 0x0000_0080, 0x0000_0084, 0x0000_0088, 0x0000_008C, 0x0000_0090,
+    0x0000_0094, 0x0000_0098, 0x0000_009C, 0x0000_00A0, 0x0000_00A4, 0x0000_00A8,
+    0x0000_00AC, 0x0000_00B0, 0x0000_00B4, 0x0000_00B8, 0x0000_00BC, 0x0000_00C0,
+    0x0000_00C4, 0x0000_00C8, 0x0000_00CC, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+  ]
+
+  static let decoding1: [UInt32] = [
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x0000_E003, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0000_F003,
+    0x0000_4003, 0x0000_5003, 0x0000_6003, 0x0000_7003, 0x0000_8003, 0x0000_9003,
+    0x0000_A003, 0x0000_B003, 0x0000_C003, 0x0000_D003, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0000_0000,
+    0x0000_1000, 0x0000_2000, 0x0000_3000, 0x0000_4000, 0x0000_5000, 0x0000_6000,
+    0x0000_7000, 0x0000_8000, 0x0000_9000, 0x0000_A000, 0x0000_B000, 0x0000_C000,
+    0x0000_D000, 0x0000_E000, 0x0000_F000, 0x0000_0001, 0x0000_1001, 0x0000_2001,
+    0x0000_3001, 0x0000_4001, 0x0000_5001, 0x0000_6001, 0x0000_7001, 0x0000_8001,
+    0x0000_9001, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x0000_A001, 0x0000_B001, 0x0000_C001, 0x0000_D001, 0x0000_E001,
+    0x0000_F001, 0x0000_0002, 0x0000_1002, 0x0000_2002, 0x0000_3002, 0x0000_4002,
+    0x0000_5002, 0x0000_6002, 0x0000_7002, 0x0000_8002, 0x0000_9002, 0x0000_A002,
+    0x0000_B002, 0x0000_C002, 0x0000_D002, 0x0000_E002, 0x0000_F002, 0x0000_0003,
+    0x0000_1003, 0x0000_2003, 0x0000_3003, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+  ]
+
+  static let decoding2: [UInt32] = [
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x0080_0F00, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x00C0_0F00,
+    0x0000_0D00, 0x0040_0D00, 0x0080_0D00, 0x00C0_0D00, 0x0000_0E00, 0x0040_0E00,
+    0x0080_0E00, 0x00C0_0E00, 0x0000_0F00, 0x0040_0F00, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0000_0000,
+    0x0040_0000, 0x0080_0000, 0x00C0_0000, 0x0000_0100, 0x0040_0100, 0x0080_0100,
+    0x00C0_0100, 0x0000_0200, 0x0040_0200, 0x0080_0200, 0x00C0_0200, 0x0000_0300,
+    0x0040_0300, 0x0080_0300, 0x00C0_0300, 0x0000_0400, 0x0040_0400, 0x0080_0400,
+    0x00C0_0400, 0x0000_0500, 0x0040_0500, 0x0080_0500, 0x00C0_0500, 0x0000_0600,
+    0x0040_0600, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x0080_0600, 0x00C0_0600, 0x0000_0700, 0x0040_0700, 0x0080_0700,
+    0x00C0_0700, 0x0000_0800, 0x0040_0800, 0x0080_0800, 0x00C0_0800, 0x0000_0900,
+    0x0040_0900, 0x0080_0900, 0x00C0_0900, 0x0000_0A00, 0x0040_0A00, 0x0080_0A00,
+    0x00C0_0A00, 0x0000_0B00, 0x0040_0B00, 0x0080_0B00, 0x00C0_0B00, 0x0000_0C00,
+    0x0040_0C00, 0x0080_0C00, 0x00C0_0C00, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+  ]
+
+  static let decoding3: [UInt32] = [
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x003E_0000, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x003F_0000,
+    0x0034_0000, 0x0035_0000, 0x0036_0000, 0x0037_0000, 0x0038_0000, 0x0039_0000,
+    0x003A_0000, 0x003B_0000, 0x003C_0000, 0x003D_0000, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0000_0000,
+    0x0001_0000, 0x0002_0000, 0x0003_0000, 0x0004_0000, 0x0005_0000, 0x0006_0000,
+    0x0007_0000, 0x0008_0000, 0x0009_0000, 0x000A_0000, 0x000B_0000, 0x000C_0000,
+    0x000D_0000, 0x000E_0000, 0x000F_0000, 0x0010_0000, 0x0011_0000, 0x0012_0000,
+    0x0013_0000, 0x0014_0000, 0x0015_0000, 0x0016_0000, 0x0017_0000, 0x0018_0000,
+    0x0019_0000, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x001A_0000, 0x001B_0000, 0x001C_0000, 0x001D_0000, 0x001E_0000,
+    0x001F_0000, 0x0020_0000, 0x0021_0000, 0x0022_0000, 0x0023_0000, 0x0024_0000,
+    0x0025_0000, 0x0026_0000, 0x0027_0000, 0x0028_0000, 0x0029_0000, 0x002A_0000,
+    0x002B_0000, 0x002C_0000, 0x002D_0000, 0x002E_0000, 0x002F_0000, 0x0030_0000,
+    0x0031_0000, 0x0032_0000, 0x0033_0000, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+  ]
+
+  static let decoding0url: [UInt32] = [
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 0
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 6
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 12
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 18
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 24
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 30
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 36
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0000_00F8, 0x01FF_FFFF, 0x01FF_FFFF,  // 42
+    0x0000_00D0, 0x0000_00D4, 0x0000_00D8, 0x0000_00DC, 0x0000_00E0, 0x0000_00E4,  // 48
+    0x0000_00E8, 0x0000_00EC, 0x0000_00F0, 0x0000_00F4, 0x01FF_FFFF, 0x01FF_FFFF,  // 54
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0000_0000,  // 60
+    0x0000_0004, 0x0000_0008, 0x0000_000C, 0x0000_0010, 0x0000_0014, 0x0000_0018,  // 66
+    0x0000_001C, 0x0000_0020, 0x0000_0024, 0x0000_0028, 0x0000_002C, 0x0000_0030,  // 72
+    0x0000_0034, 0x0000_0038, 0x0000_003C, 0x0000_0040, 0x0000_0044, 0x0000_0048,  // 78
+    0x0000_004C, 0x0000_0050, 0x0000_0054, 0x0000_0058, 0x0000_005C, 0x0000_0060,  // 84
+    0x0000_0064, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0000_00FC,  // 90
+    0x01FF_FFFF, 0x0000_0068, 0x0000_006C, 0x0000_0070, 0x0000_0074, 0x0000_0078,
+    0x0000_007C, 0x0000_0080, 0x0000_0084, 0x0000_0088, 0x0000_008C, 0x0000_0090,
+    0x0000_0094, 0x0000_0098, 0x0000_009C, 0x0000_00A0, 0x0000_00A4, 0x0000_00A8,
+    0x0000_00AC, 0x0000_00B0, 0x0000_00B4, 0x0000_00B8, 0x0000_00BC, 0x0000_00C0,
+    0x0000_00C4, 0x0000_00C8, 0x0000_00CC, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+  ]
+
+  static let decoding1url: [UInt32] = [
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 0
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 6
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 12
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 18
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 24
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 30
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 36
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0000_E003, 0x01FF_FFFF, 0x01FF_FFFF,  // 42
+    0x0000_4003, 0x0000_5003, 0x0000_6003, 0x0000_7003, 0x0000_8003, 0x0000_9003,  // 48
+    0x0000_A003, 0x0000_B003, 0x0000_C003, 0x0000_D003, 0x01FF_FFFF, 0x01FF_FFFF,  // 54
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0000_0000,  // 60
+    0x0000_1000, 0x0000_2000, 0x0000_3000, 0x0000_4000, 0x0000_5000, 0x0000_6000,  // 66
+    0x0000_7000, 0x0000_8000, 0x0000_9000, 0x0000_A000, 0x0000_B000, 0x0000_C000,  // 72
+    0x0000_D000, 0x0000_E000, 0x0000_F000, 0x0000_0001, 0x0000_1001, 0x0000_2001,  // 78
+    0x0000_3001, 0x0000_4001, 0x0000_5001, 0x0000_6001, 0x0000_7001, 0x0000_8001,  // 84
+    0x0000_9001, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0000_F003,  // 90
+    0x01FF_FFFF, 0x0000_A001, 0x0000_B001, 0x0000_C001, 0x0000_D001, 0x0000_E001,
+    0x0000_F001, 0x0000_0002, 0x0000_1002, 0x0000_2002, 0x0000_3002, 0x0000_4002,
+    0x0000_5002, 0x0000_6002, 0x0000_7002, 0x0000_8002, 0x0000_9002, 0x0000_A002,
+    0x0000_B002, 0x0000_C002, 0x0000_D002, 0x0000_E002, 0x0000_F002, 0x0000_0003,
+    0x0000_1003, 0x0000_2003, 0x0000_3003, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+  ]
+
+  static let decoding2url: [UInt32] = [
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 0
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 6
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 12
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 18
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 24
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 30
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 36
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0080_0F00, 0x01FF_FFFF, 0x01FF_FFFF,  // 42
+    0x0000_0D00, 0x0040_0D00, 0x0080_0D00, 0x00C0_0D00, 0x0000_0E00, 0x0040_0E00,  // 48
+    0x0080_0E00, 0x00C0_0E00, 0x0000_0F00, 0x0040_0F00, 0x01FF_FFFF, 0x01FF_FFFF,  // 54
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0000_0000,  // 60
+    0x0040_0000, 0x0080_0000, 0x00C0_0000, 0x0000_0100, 0x0040_0100, 0x0080_0100,  // 66
+    0x00C0_0100, 0x0000_0200, 0x0040_0200, 0x0080_0200, 0x00C0_0200, 0x0000_0300,  // 72
+    0x0040_0300, 0x0080_0300, 0x00C0_0300, 0x0000_0400, 0x0040_0400, 0x0080_0400,  // 78
+    0x00C0_0400, 0x0000_0500, 0x0040_0500, 0x0080_0500, 0x00C0_0500, 0x0000_0600,  // 84
+    0x0040_0600, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x00C0_0F00,  // 90
+    0x01FF_FFFF, 0x0080_0600, 0x00C0_0600, 0x0000_0700, 0x0040_0700, 0x0080_0700,
+    0x00C0_0700, 0x0000_0800, 0x0040_0800, 0x0080_0800, 0x00C0_0800, 0x0000_0900,
+    0x0040_0900, 0x0080_0900, 0x00C0_0900, 0x0000_0A00, 0x0040_0A00, 0x0080_0A00,
+    0x00C0_0A00, 0x0000_0B00, 0x0040_0B00, 0x0080_0B00, 0x00C0_0B00, 0x0000_0C00,
+    0x0040_0C00, 0x0080_0C00, 0x00C0_0C00, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+  ]
+
+  static let decoding3url: [UInt32] = [
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 0
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 6
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 12
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 18
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 24
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 30
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,  // 36
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x003E_0000, 0x01FF_FFFF, 0x01FF_FFFF,  // 42
+    0x0034_0000, 0x0035_0000, 0x0036_0000, 0x0037_0000, 0x0038_0000, 0x0039_0000,  // 48
+    0x003A_0000, 0x003B_0000, 0x003C_0000, 0x003D_0000, 0x01FF_FFFF, 0x01FF_FFFF,  // 54
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x0000_0000,  // 60
+    0x0001_0000, 0x0002_0000, 0x0003_0000, 0x0004_0000, 0x0005_0000, 0x0006_0000,  // 66
+    0x0007_0000, 0x0008_0000, 0x0009_0000, 0x000A_0000, 0x000B_0000, 0x000C_0000,  // 72
+    0x000D_0000, 0x000E_0000, 0x000F_0000, 0x0010_0000, 0x0011_0000, 0x0012_0000,  // 78
+    0x0013_0000, 0x0014_0000, 0x0015_0000, 0x0016_0000, 0x0017_0000, 0x0018_0000,  // 84
+    0x0019_0000, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x003F_0000,  // 90
+    0x01FF_FFFF, 0x001A_0000, 0x001B_0000, 0x001C_0000, 0x001D_0000, 0x001E_0000,
+    0x001F_0000, 0x0020_0000, 0x0021_0000, 0x0022_0000, 0x0023_0000, 0x0024_0000,
+    0x0025_0000, 0x0026_0000, 0x0027_0000, 0x0028_0000, 0x0029_0000, 0x002A_0000,
+    0x002B_0000, 0x002C_0000, 0x002D_0000, 0x002E_0000, 0x002F_0000, 0x0030_0000,
+    0x0031_0000, 0x0032_0000, 0x0033_0000, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+    0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF, 0x01FF_FFFF,
+  ]
+}
diff --git a/Sources/GRPCCore/Internal/Concurrency Primities/Lock.swift b/Sources/GRPCCore/Internal/Concurrency Primitives/Lock.swift
similarity index 100%
rename from Sources/GRPCCore/Internal/Concurrency Primities/Lock.swift
rename to Sources/GRPCCore/Internal/Concurrency Primitives/Lock.swift
diff --git a/Sources/GRPCCore/Internal/String+Extensions.swift b/Sources/GRPCCore/Internal/String+Extensions.swift
new file mode 100644
index 000000000..f230c1ffe
--- /dev/null
+++ b/Sources/GRPCCore/Internal/String+Extensions.swift
@@ -0,0 +1,80 @@
+/*
+ * Copyright 2023, gRPC Authors All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftNIO open source project
+//
+// Copyright (c) 2017-2023 Apple Inc. and the SwiftNIO project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftNIO project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+extension UInt8 {
+  @inlinable
+  var isASCII: Bool {
+    return self <= 127
+  }
+}
+
+extension String.UTF8View {
+  /// Compares two UTF8 strings as case insensitive ASCII bytes.
+  ///
+  /// - Parameter bytes: The string constant in the form of a collection of `UInt8`
+  /// - Returns: Whether the collection contains **EXACTLY** this array or no, but by ignoring case.
+  @inlinable
+  func compareCaseInsensitiveASCIIBytes(to other: String.UTF8View) -> Bool {
+    // fast path: we can get the underlying bytes of both
+    let maybeMaybeResult = self.withContiguousStorageIfAvailable { lhsBuffer -> Bool? in
+      other.withContiguousStorageIfAvailable { rhsBuffer in
+        if lhsBuffer.count != rhsBuffer.count {
+          return false
+        }
+
+        for idx in 0 ..< lhsBuffer.count {
+          // let's hope this gets vectorised ;)
+          if lhsBuffer[idx] & 0xdf != rhsBuffer[idx] & 0xdf && lhsBuffer[idx].isASCII {
+            return false
+          }
+        }
+        return true
+      }
+    }
+
+    if let maybeResult = maybeMaybeResult, let result = maybeResult {
+      return result
+    } else {
+      return self._compareCaseInsensitiveASCIIBytesSlowPath(to: other)
+    }
+  }
+
+  @inlinable
+  @inline(never)
+  func _compareCaseInsensitiveASCIIBytesSlowPath(to other: String.UTF8View) -> Bool {
+    return self.elementsEqual(other, by: { return (($0 & 0xdf) == ($1 & 0xdf) && $0.isASCII) })
+  }
+}
+
+extension String {
+  @inlinable
+  func isEqualCaseInsensitiveASCIIBytes(to: String) -> Bool {
+    return self.utf8.compareCaseInsensitiveASCIIBytes(to: to.utf8)
+  }
+}
diff --git a/Sources/GRPCCore/Metadata.swift b/Sources/GRPCCore/Metadata.swift
index 5a72fd161..0b2e560f8 100644
--- a/Sources/GRPCCore/Metadata.swift
+++ b/Sources/GRPCCore/Metadata.swift
@@ -14,5 +14,455 @@
  * limitations under the License.
  */
 
-// FIXME: placeholder.
-public typealias Metadata = [String: String]
+/// A collection of metadata key-value pairs, found in RPC streams.
+///
+/// Metadata is a side channel associated with an RPC, that allows you to send information between clients
+/// and servers. Metadata is stored as a list of key-value pairs where keys aren't required to be unique;
+/// a single key may have multiple values associated with it.
+///
+/// Keys are case-insensitive ASCII strings. Values may be ASCII strings or binary data. The keys
+/// for binary data should end with "-bin": this will be asserted when adding a new binary value.
+/// Keys must not be prefixed with "grpc-" as these are reserved for gRPC.
+///
+/// # Using Metadata
+///
+/// You can add values to ``Metadata`` using the ``addString(_:forKey:)`` and
+/// ``addBinary(_:forKey:)`` methods:
+///
+/// ```swift
+/// var metadata = Metadata()
+/// metadata.addString("value", forKey: "key")
+/// metadata.addBinary([118, 97, 108, 117, 101], forKey: "key-bin")
+/// ```
+///
+/// As ``Metadata`` conforms to `RandomAccessCollection` you can iterate over its values.
+/// Because metadata can store strings and binary values, its `Element` type is an `enum` representing
+/// both possibilities:
+///
+/// ```swift
+/// for (key, value) in metadata {
+///   switch value {
+///   case .string(let value):
+///     print("'\(key)' has a string value: '\(value)'")
+///   case .binary(let value):
+///     print("'\(key)' has a binary value: '\(value)'")
+///   }
+/// }
+/// ```
+///
+/// You can also iterate over the values for a specific key:
+///
+/// ```swift
+/// for value in metadata["key"] {
+///   switch value {
+///   case .string(let value):
+///     print("'key' has a string value: '\(value)'")
+///   case .binary(let value):
+///     print("'key' has a binary value: '\(value)'")
+///   }
+/// }
+/// ```
+///
+/// You can get only string or binary values for a key using ``subscript(stringValues:)`` and
+/// ``subscript(binaryValues:)``:
+///
+/// ```swift
+/// for value in metadata[stringValues: "key"] {
+///   print("'key' has a string value: '\(value)'")
+/// }
+///
+/// for value in metadata[binaryValues: "key"] {
+///   print("'key' has a binary value: '\(value)'")
+/// }
+/// ```
+///
+/// - Note: Binary values are encoded as base64 strings when they are sent over the wire, so keys with
+/// the "-bin" suffix may have string values (rather than binary). These are deserialized automatically when
+/// using ``subscript(binaryValues:)``.
+public struct Metadata: Sendable, Hashable {
+
+  /// A metadata value. It can either be a simple string, or binary data.
+  public enum Value: Sendable, Hashable {
+    case string(String)
+    case binary([UInt8])
+  }
+
+  /// A metadata key-value pair.
+  internal struct KeyValuePair: Sendable, Hashable {
+    internal let key: String
+    internal let value: Value
+
+    /// Constructor for a metadata key-value pair.
+    ///
+    /// - Parameters:
+    ///   - key: The key for the key-value pair.
+    ///   - value: The value to be associated to the given key. If it's a binary value, then the associated
+    ///   key must end in "-bin", otherwise, this method will produce an assertion failure.
+    init(key: String, value: Value) {
+      if case .binary = value {
+        assert(key.hasSuffix("-bin"), "Keys for binary values must end in -bin")
+      }
+      self.key = key
+      self.value = value
+    }
+  }
+
+  private var elements: [KeyValuePair]
+
+  /// The Metadata collection's capacity.
+  public var capacity: Int {
+    self.elements.capacity
+  }
+
+  /// Initialize an empty Metadata collection.
+  public init() {
+    self.elements = []
+  }
+
+  /// Reserve the specified minimum capacity in the collection.
+  ///
+  /// - Parameter minimumCapacity: The minimum capacity to reserve in the collection.
+  public mutating func reserveCapacity(_ minimumCapacity: Int) {
+    self.elements.reserveCapacity(minimumCapacity)
+  }
+
+  /// Add a new key-value pair, where the value is a string.
+  ///
+  /// - Parameters:
+  ///   - stringValue: The string value to be associated with the given key.
+  ///   - key: The key to be associated with the given value.
+  public mutating func addString(_ stringValue: String, forKey key: String) {
+    self.addValue(.string(stringValue), forKey: key)
+  }
+
+  /// Add a new key-value pair, where the value is binary data, in the form of `[UInt8]`.
+  ///
+  /// - Parameters:
+  ///   - binaryValue: The binary data (i.e., `[UInt8]`) to be associated with the given key.
+  ///   - key: The key to be associated with the given value. Must end in "-bin".
+  public mutating func addBinary(_ binaryValue: [UInt8], forKey key: String) {
+    self.addValue(.binary(binaryValue), forKey: key)
+  }
+
+  /// Add a new key-value pair.
+  ///
+  /// - Parameters:
+  ///   - value: The ``Value`` to be associated with the given key.
+  ///   - key: The key to be associated with the given value. If value is binary, it must end in "-bin".
+  internal mutating func addValue(_ value: Value, forKey key: String) {
+    self.elements.append(.init(key: key, value: value))
+  }
+
+  /// Removes all values associated with the given key.
+  ///
+  /// - Parameter key: The key for which all values should be removed.
+  ///
+  /// - Complexity: O(*n*), where *n* is the number of entries in the metadata instance.
+  public mutating func removeAllValues(forKey key: String) {
+    elements.removeAll { metadataKeyValue in
+      metadataKeyValue.key.isEqualCaseInsensitiveASCIIBytes(to: key)
+    }
+  }
+
+  /// Adds a key-value pair to the collection, where the value is a string.
+  ///
+  /// If there are pairs already associated to the given key, they will all be removed first, and the new pair
+  /// will be added. If no pairs are present with the given key, a new one will be added.
+  ///
+  /// - Parameters:
+  ///   - stringValue: The string value to be associated with the given key.
+  ///   - key: The key to be associated with the given value.
+  ///
+  /// - Complexity: O(*n*), where *n* is the number of entries in the metadata instance.
+  public mutating func replaceOrAddString(_ stringValue: String, forKey key: String) {
+    self.replaceOrAddValue(.string(stringValue), forKey: key)
+  }
+
+  /// Adds a key-value pair to the collection, where the value is `[UInt8]`.
+  ///
+  /// If there are pairs already associated to the given key, they will all be removed first, and the new pair
+  /// will be added. If no pairs are present with the given key, a new one will be added.
+  ///
+  /// - Parameters:
+  ///   - binaryValue: The `[UInt8]` to be associated with the given key.
+  ///   - key: The key to be associated with the given value. Must end in "-bin".
+  ///
+  /// - Complexity: O(*n*), where *n* is the number of entries in the metadata instance.
+  public mutating func replaceOrAddBinary(_ binaryValue: [UInt8], forKey key: String) {
+    self.replaceOrAddValue(.binary(binaryValue), forKey: key)
+  }
+
+  /// Adds a key-value pair to the collection.
+  ///
+  /// If there are pairs already associated to the given key, they will all be removed first, and the new pair
+  /// will be added. If no pairs are present with the given key, a new one will be added.
+  ///
+  /// - Parameters:
+  ///   - value: The ``Value`` to be associated with the given key.
+  ///   - key: The key to be associated with the given value. If value is binary, it must end in "-bin".
+  ///
+  /// - Complexity: O(*n*), where *n* is the number of entries in the metadata instance.
+  internal mutating func replaceOrAddValue(_ value: Value, forKey key: String) {
+    self.removeAllValues(forKey: key)
+    self.elements.append(.init(key: key, value: value))
+  }
+
+  /// Removes all key-value pairs from this metadata instance.
+  ///
+  /// - Parameter keepingCapacity: Whether the current capacity should be kept or reset.
+  ///
+  /// - Complexity: O(*n*), where *n* is the number of entries in the metadata instance.
+  public mutating func removeAll(keepingCapacity: Bool) {
+    self.elements.removeAll(keepingCapacity: keepingCapacity)
+  }
+}
+
+extension Metadata: RandomAccessCollection {
+  public typealias Element = (key: String, value: Value)
+
+  public struct Index: Comparable, Sendable {
+    @usableFromInline
+    let _base: Array<Element>.Index
+
+    @inlinable
+    init(_base: Array<Element>.Index) {
+      self._base = _base
+    }
+
+    @inlinable
+    public static func < (lhs: Index, rhs: Index) -> Bool {
+      return lhs._base < rhs._base
+    }
+  }
+
+  public var startIndex: Index {
+    return .init(_base: self.elements.startIndex)
+  }
+
+  public var endIndex: Index {
+    return .init(_base: self.elements.endIndex)
+  }
+
+  public func index(before i: Index) -> Index {
+    return .init(_base: self.elements.index(before: i._base))
+  }
+
+  public func index(after i: Index) -> Index {
+    return .init(_base: self.elements.index(after: i._base))
+  }
+
+  public subscript(position: Index) -> Element {
+    let keyValuePair = self.elements[position._base]
+    return (key: keyValuePair.key, value: keyValuePair.value)
+  }
+}
+
+extension Metadata {
+
+  /// A sequence of metadata values for a given key.
+  public struct Values: Sequence {
+
+    /// An iterator for all metadata ``Value``s associated with a given key.
+    public struct Iterator: IteratorProtocol {
+      private var metadataIterator: Metadata.Iterator
+      private let key: String
+
+      init(forKey key: String, metadata: Metadata) {
+        self.metadataIterator = metadata.makeIterator()
+        self.key = key
+      }
+
+      public mutating func next() -> Value? {
+        while let nextKeyValue = self.metadataIterator.next() {
+          if nextKeyValue.key.isEqualCaseInsensitiveASCIIBytes(to: self.key) {
+            return nextKeyValue.value
+          }
+        }
+        return nil
+      }
+    }
+
+    private let key: String
+    private let metadata: Metadata
+
+    internal init(key: String, metadata: Metadata) {
+      self.key = key
+      self.metadata = metadata
+    }
+
+    public func makeIterator() -> Iterator {
+      Iterator(forKey: self.key, metadata: self.metadata)
+    }
+  }
+
+  /// Get a ``Values`` sequence for a given key.
+  ///
+  /// - Parameter key: The returned sequence will only return values for this key.
+  ///
+  /// - Returns: A sequence containing all values for the given key.
+  public subscript(_ key: String) -> Values {
+    Values(key: key, metadata: self)
+  }
+}
+
+extension Metadata {
+
+  /// A sequence of metadata string values for a given key.
+  public struct StringValues: Sequence {
+
+    /// An iterator for all string values associated with a given key.
+    ///
+    /// This iterator will only return values originally stored as strings for a given key.
+    public struct Iterator: IteratorProtocol {
+      private var values: Values.Iterator
+
+      init(values: Values) {
+        self.values = values.makeIterator()
+      }
+
+      public mutating func next() -> String? {
+        while let value = self.values.next() {
+          switch value {
+          case .string(let stringValue):
+            return stringValue
+          case .binary:
+            continue
+          }
+        }
+        return nil
+      }
+    }
+
+    private let key: String
+    private let metadata: Metadata
+
+    internal init(key: String, metadata: Metadata) {
+      self.key = key
+      self.metadata = metadata
+    }
+
+    public func makeIterator() -> Iterator {
+      Iterator(values: Values(key: self.key, metadata: self.metadata))
+    }
+  }
+
+  /// Get a ``StringValues`` sequence for a given key.
+  ///
+  /// - Parameter key: The returned sequence will only return string values for this key.
+  ///
+  /// - Returns: A sequence containing string values for the given key.
+  public subscript(stringValues key: String) -> StringValues {
+    StringValues(key: key, metadata: self)
+  }
+}
+
+extension Metadata {
+
+  /// A sequence of metadata binary values for a given key.
+  public struct BinaryValues: Sequence {
+
+    /// An iterator for all binary data values associated with a given key.
+    ///
+    /// This iterator will return values originally stored as binary data for a given key, and will also try to
+    /// decode values stored as strings as if they were base64-encoded strings.
+    public struct Iterator: IteratorProtocol {
+      private var values: Values.Iterator
+
+      init(values: Values) {
+        self.values = values.makeIterator()
+      }
+
+      public mutating func next() -> [UInt8]? {
+        while let value = self.values.next() {
+          switch value {
+          case .string(let stringValue):
+            do {
+              return try Base64.decode(string: stringValue)
+            } catch {
+              continue
+            }
+          case .binary(let binaryValue):
+            return binaryValue
+          }
+        }
+        return nil
+      }
+    }
+
+    private let key: String
+    private let metadata: Metadata
+
+    internal init(key: String, metadata: Metadata) {
+      self.key = key
+      self.metadata = metadata
+    }
+
+    public func makeIterator() -> Iterator {
+      Iterator(values: Values(key: self.key, metadata: self.metadata))
+    }
+  }
+
+  /// A subscript to get a ``BinaryValues`` sequence for a given key.
+  ///
+  /// As it's iterated, this sequence will return values originally stored as binary data for a given key, and will
+  /// also try to decode values stored as strings as if they were base64-encoded strings; only strings that
+  /// are successfully decoded will be returned.
+  ///
+  /// - Parameter key: The returned sequence will only return binary (i.e. `[UInt8]`) values for this key.
+  ///
+  /// - Returns: A sequence containing binary (i.e. `[UInt8]`) values for the given key.
+  ///
+  /// - SeeAlso: ``BinaryValues/Iterator``.
+  public subscript(binaryValues key: String) -> BinaryValues {
+    BinaryValues(key: key, metadata: self)
+  }
+}
+
+extension Metadata: ExpressibleByDictionaryLiteral {
+  public init(dictionaryLiteral elements: (String, Value)...) {
+    self.elements = elements.map { KeyValuePair(key: $0, value: $1) }
+  }
+}
+
+extension Metadata: ExpressibleByArrayLiteral {
+  public init(arrayLiteral elements: (String, Value)...) {
+    self.elements = elements.map { KeyValuePair(key: $0, value: $1) }
+  }
+}
+
+extension Metadata.Value: ExpressibleByStringLiteral {
+  public init(stringLiteral value: StringLiteralType) {
+    self = .string(value)
+  }
+}
+
+extension Metadata.Value: ExpressibleByStringInterpolation {
+  public init(stringInterpolation: DefaultStringInterpolation) {
+    self = .string(String(stringInterpolation: stringInterpolation))
+  }
+}
+
+extension Metadata.Value: ExpressibleByArrayLiteral {
+  public typealias ArrayLiteralElement = UInt8
+
+  public init(arrayLiteral elements: ArrayLiteralElement...) {
+    self = .binary(elements)
+  }
+}
+
+extension Metadata: CustomStringConvertible {
+  public var description: String {
+    String(describing: self.map({ ($0.key, $0.value) }))
+  }
+}
+
+extension Metadata.Value: CustomStringConvertible {
+  public var description: String {
+    switch self {
+    case .string(let stringValue):
+      return String(describing: stringValue)
+    case .binary(let binaryValue):
+      return String(describing: binaryValue)
+    }
+  }
+}
diff --git a/Tests/GRPCCoreTests/MetadataTests.swift b/Tests/GRPCCoreTests/MetadataTests.swift
new file mode 100644
index 000000000..fca7125b0
--- /dev/null
+++ b/Tests/GRPCCoreTests/MetadataTests.swift
@@ -0,0 +1,208 @@
+/*
+ * Copyright 2023, gRPC Authors All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import GRPCCore
+import XCTest
+
+final class MetadataTests: XCTestCase {
+  func testAddStringValue() {
+    var metadata = Metadata()
+    XCTAssertTrue(metadata.isEmpty)
+
+    metadata.addString("testValue", forKey: "testString")
+    XCTAssertEqual(metadata.count, 1)
+
+    let sequence = metadata[stringValues: "testString"]
+    var iterator = sequence.makeIterator()
+    XCTAssertEqual(iterator.next(), "testValue")
+    XCTAssertNil(iterator.next())
+  }
+
+  func testAddBinaryValue() {
+    var metadata = Metadata()
+    XCTAssertTrue(metadata.isEmpty)
+
+    metadata.addBinary(Array("base64encodedString".utf8), forKey: "testBinary-bin")
+    XCTAssertEqual(metadata.count, 1)
+
+    let sequence = metadata[binaryValues: "testBinary-bin"]
+    var iterator = sequence.makeIterator()
+    XCTAssertEqual(iterator.next(), Array("base64encodedString".utf8))
+    XCTAssertNil(iterator.next())
+  }
+
+  func testCreateFromDictionaryLiteral() {
+    let metadata: Metadata = [
+      "testKey": "stringValue",
+      "testKey-bin": .binary(Array("base64encodedString".utf8)),
+    ]
+    XCTAssertEqual(metadata.count, 2)
+
+    let stringSequence = metadata[stringValues: "testKey"]
+    var stringIterator = stringSequence.makeIterator()
+    XCTAssertEqual(stringIterator.next(), "stringValue")
+    XCTAssertNil(stringIterator.next())
+
+    let binarySequence = metadata[binaryValues: "testKey-bin"]
+    var binaryIterator = binarySequence.makeIterator()
+    XCTAssertEqual(binaryIterator.next(), Array("base64encodedString".utf8))
+    XCTAssertNil(binaryIterator.next())
+  }
+
+  func testReplaceOrAddValue() {
+    var metadata: Metadata = [
+      "testKey": "value1",
+      "testKey": "value2",
+    ]
+    XCTAssertEqual(metadata.count, 2)
+
+    var sequence = metadata[stringValues: "testKey"]
+    var iterator = sequence.makeIterator()
+    XCTAssertEqual(iterator.next(), "value1")
+    XCTAssertEqual(iterator.next(), "value2")
+    XCTAssertNil(iterator.next())
+
+    metadata.replaceOrAddString("anotherValue", forKey: "testKey2")
+    XCTAssertEqual(metadata.count, 3)
+    sequence = metadata[stringValues: "testKey"]
+    iterator = sequence.makeIterator()
+    XCTAssertEqual(iterator.next(), "value1")
+    XCTAssertEqual(iterator.next(), "value2")
+    XCTAssertNil(iterator.next())
+    sequence = metadata[stringValues: "testKey2"]
+    iterator = sequence.makeIterator()
+    XCTAssertEqual(iterator.next(), "anotherValue")
+    XCTAssertNil(iterator.next())
+
+    metadata.replaceOrAddString("newValue", forKey: "testKey")
+    XCTAssertEqual(metadata.count, 2)
+    sequence = metadata[stringValues: "testKey"]
+    iterator = sequence.makeIterator()
+    XCTAssertEqual(iterator.next(), "newValue")
+    XCTAssertNil(iterator.next())
+    sequence = metadata[stringValues: "testKey2"]
+    iterator = sequence.makeIterator()
+    XCTAssertEqual(iterator.next(), "anotherValue")
+    XCTAssertNil(iterator.next())
+  }
+
+  func testReserveCapacity() {
+    var metadata = Metadata()
+    XCTAssertEqual(metadata.capacity, 0)
+
+    metadata.reserveCapacity(10)
+    XCTAssertEqual(metadata.capacity, 10)
+  }
+
+  func testValuesIteration() {
+    let metadata: Metadata = [
+      "testKey-bin": "string1",
+      "testKey-bin": .binary(.init("data1".utf8)),
+      "testKey-bin": "string2",
+      "testKey-bin": .binary(.init("data2".utf8)),
+      "testKey-bin": "string3",
+      "testKey-bin": .binary(.init("data3".utf8)),
+    ]
+    XCTAssertEqual(metadata.count, 6)
+
+    let sequence = metadata["testKey-bin"]
+    var iterator = sequence.makeIterator()
+    XCTAssertEqual(iterator.next(), .string("string1"))
+    XCTAssertEqual(iterator.next(), .binary(.init("data1".utf8)))
+    XCTAssertEqual(iterator.next(), .string("string2"))
+    XCTAssertEqual(iterator.next(), .binary(.init("data2".utf8)))
+    XCTAssertEqual(iterator.next(), .string("string3"))
+    XCTAssertEqual(iterator.next(), .binary(.init("data3".utf8)))
+    XCTAssertNil(iterator.next())
+  }
+
+  func testStringValuesIteration() {
+    let metadata: Metadata = [
+      "testKey-bin": "string1",
+      "testKey-bin": .binary(.init("data1".utf8)),
+      "testKey-bin": "string2",
+      "testKey-bin": .binary(.init("data2".utf8)),
+      "testKey-bin": "string3",
+      "testKey-bin": .binary(.init("data3".utf8)),
+    ]
+    XCTAssertEqual(metadata.count, 6)
+
+    let stringSequence = metadata[stringValues: "testKey-bin"]
+    var stringIterator = stringSequence.makeIterator()
+    XCTAssertEqual(stringIterator.next(), "string1")
+    XCTAssertEqual(stringIterator.next(), "string2")
+    XCTAssertEqual(stringIterator.next(), "string3")
+    XCTAssertNil(stringIterator.next())
+  }
+
+  func testBinaryValuesIteration_InvalidBase64EncodedStrings() {
+    let metadata: Metadata = [
+      "testKey-bin": "invalidBase64-1",
+      "testKey-bin": .binary(.init("data1".utf8)),
+      "testKey-bin": "invalidBase64-2",
+      "testKey-bin": .binary(.init("data2".utf8)),
+      "testKey-bin": "invalidBase64-3",
+      "testKey-bin": .binary(.init("data3".utf8)),
+    ]
+    XCTAssertEqual(metadata.count, 6)
+
+    let binarySequence = metadata[binaryValues: "testKey-bin"]
+    var binaryIterator = binarySequence.makeIterator()
+    XCTAssertEqual(binaryIterator.next(), Array("data1".utf8))
+    XCTAssertEqual(binaryIterator.next(), Array("data2".utf8))
+    XCTAssertEqual(binaryIterator.next(), Array("data3".utf8))
+    XCTAssertNil(binaryIterator.next())
+  }
+
+  func testBinaryValuesIteration_ValidBase64EncodedStrings() {
+    let metadata: Metadata = [
+      "testKey-bin": "c3RyaW5nMQ==",
+      "testKey-bin": .binary(.init("data1".utf8)),
+      "testKey-bin": "c3RyaW5nMg==",
+      "testKey-bin": .binary(.init("data2".utf8)),
+      "testKey-bin": "c3RyaW5nMw==",
+      "testKey-bin": .binary(.init("data3".utf8)),
+    ]
+    XCTAssertEqual(metadata.count, 6)
+
+    let binarySequence = metadata[binaryValues: "testKey-bin"]
+    var binaryIterator = binarySequence.makeIterator()
+    XCTAssertEqual(binaryIterator.next(), Array("string1".utf8))
+    XCTAssertEqual(binaryIterator.next(), Array("data1".utf8))
+    XCTAssertEqual(binaryIterator.next(), Array("string2".utf8))
+    XCTAssertEqual(binaryIterator.next(), Array("data2".utf8))
+    XCTAssertEqual(binaryIterator.next(), Array("string3".utf8))
+    XCTAssertEqual(binaryIterator.next(), Array("data3".utf8))
+    XCTAssertNil(binaryIterator.next())
+  }
+
+  func testKeysAreCaseInsensitive() {
+    let metadata: Metadata = [
+      "testkey1": "value1",
+      "TESTKEY2": "value2",
+    ]
+    XCTAssertEqual(metadata.count, 2)
+
+    var stringSequence = metadata[stringValues: "TESTKEY1"]
+    var stringIterator = stringSequence.makeIterator()
+    XCTAssertEqual(stringIterator.next(), "value1")
+    XCTAssertNil(stringIterator.next())
+
+    stringSequence = metadata[stringValues: "testkey2"]
+    stringIterator = stringSequence.makeIterator()
+    XCTAssertEqual(stringIterator.next(), "value2")
+    XCTAssertNil(stringIterator.next())
+  }
+}
diff --git a/Tests/GRPCTests/GRPCTestCase.swift b/Tests/GRPCTests/GRPCTestCase.swift
index 0adba1cd3..3c9747265 100644
--- a/Tests/GRPCTests/GRPCTestCase.swift
+++ b/Tests/GRPCTests/GRPCTestCase.swift
@@ -38,7 +38,7 @@ class GRPCTestCase: XCTestCase {
   override func tearDown() {
     // Only print logs when there's a failure and we're *not* always logging (when we are always
     // logging, logs will be printed as they're caught).
-    if !GRPCTestCase.alwaysLog, self.testRun.map { $0.totalFailureCount > 0 } ?? false {
+    if !GRPCTestCase.alwaysLog, self.testRun.map({ $0.totalFailureCount > 0 }) ?? false {
       let logs = self.capturedLogs()
       self.printCapturedLogs(logs)
     }