Correct redaction of Array.Empty<char>() and new char[0]

Fixes #4308

src/Libraries/Microsoft.Extensions.Compliance.Abstractions/Redaction/Redactor.cs

@@ -191,9 +191,14 @@ public int Redact<T>(T value, Span<char> destination, string? format = null, IFo
             return Redact(((IFormattable)value).ToString(format, provider), destination);
         }
 
-        if (value is char[] arrayOfChar)
+        if (value is char[])
         {
-            return Redact(arrayOfChar.AsSpan(), destination);
+            // An attempt to call value.ToString() on a char[] will produce a string "System.Char[]" and all redaction will be attempted on it,
+            // instead of the provided array. This will lead to incorrectly allocated buffers.
+            //
+            // NB: not using pattern matching as it is recognized by the JIT and since this is a generic type, the JIT ends up generating code
+            // without any of those conditional statements being present. But this only happens when not using pattern matching.
+            return Redact(((char[])(object)value).AsSpan(), destination);
         }
 
         return Redact(value?.ToString(), destination);