Try dotnet/java-interop#1302

.gitmodules

@@ -13,7 +13,7 @@
 [submodule "external/Java.Interop"]
     path = external/Java.Interop
     url = https://github.com/dotnet/java-interop
-    branch = main
+    branch = dev/jonp/jonp-dotnet-requires-plus-not-slash
 [submodule "external/libunwind"]
     path = external/libunwind
     url = https://github.com/libunwind/libunwind.git

build-tools/Xamarin.Android.Tools.BootstrapTasks/Xamarin.Android.Tools.BootstrapTasks/CheckApiCompatibility.cs

@@ -67,6 +67,9 @@ public sealed class CheckApiCompatibility : Task
 		// In case API diffs vary between e.g. Classic MonoAndroid & .NET 6+
 		public string TargetFramework { get; set; }
 
+		// What's missing from acceptableIssuesFile?
+		public string LinesToAdd { get; set; }
+
 		// This Build tasks validates that changes are not breaking Api
 		public override bool Execute ()
 		{
@@ -260,6 +263,7 @@ void dataReceived (object sender, DataReceivedEventArgs args)
 					}
 
 					LogError ($"CheckApiCompatibility found nonacceptable Api breakages for ApiLevel: {ApiLevel}.{Environment.NewLine}{string.Join (Environment.NewLine, lines)}");
+					ReportMissingLines (acceptableIssuesFile.FullName, lines);
 
 					var missingItems = CodeGenDiff.GenerateMissingItems (CodeGenPath, contractAssembly.FullName, implementationAssembly.FullName);
 					if (missingItems.Any ()) {
@@ -285,6 +289,21 @@ void dataReceived (object sender, DataReceivedEventArgs args)
 			}
 		}
 
+		void ReportMissingLines (string acceptableIssuesFile, List<string> lines)
+		{
+			if (string.IsNullOrWhiteSpace (LinesToAdd)) {
+				return;
+			}
+			var known = new HashSet<string> (File.ReadAllLines (acceptableIssuesFile), StringComparer.Ordinal);
+			using var writer = File.CreateText (LinesToAdd);
+			foreach (var line in lines) {
+				if (known.Contains (line)) {
+					continue;
+				}
+				writer.WriteLine (line);
+			}
+		}
+
 		void LogError (string errorMessage)
 		{
 			if (!string.IsNullOrWhiteSpace (compatApiCommand)) {

src/Microsoft.Android.Sdk.ILLink/MarkJavaObjects.cs

@@ -232,7 +232,7 @@ string TypeNameWithoutKey (string name)
 
 		bool CheckInvokerType (TypeDefinition type, string name)
 		{
-			return TypeNameWithoutKey (name) == TypeNameWithoutKey ($"{ type.FullName}, { type.Module.Assembly.FullName}");
+			return TypeNameWithoutKey (name.Replace ('+', '/')) == TypeNameWithoutKey ($"{ type.FullName}, { type.Module.Assembly.FullName}");
 		}
 
 		void PreserveInterfaceMethods (TypeDefinition type, TypeDefinition invoker)

src/Mono.Android/Mono.Android.targets

@@ -225,6 +225,7 @@
         TargetImplementationPath="$(OutputPath)"
         ApiCompatibilityPath="$(ApiCompatibilityDir)"
         TargetFramework="$(TargetFramework)"
+        LinesToAdd="$(MSBuildThisFileDirectory)ApiCompatLinesToAdd.txt"
     />
     <Touch
         Files="$(IntermediateOutputPath)CheckApiCompatibility.stamp"

src/Xamarin.Android.Build.Tasks/Linker/MonoDroid.Tuner/Extensions.cs

@@ -116,7 +116,7 @@ public static MethodDefinition GetMethod (TypeDefinition type, string name, stri
 
 		public static TypeDefinition GetType (AssemblyDefinition assembly, string typeName)
 		{
-			return assembly.MainModule.GetType (typeName);
+			return assembly.MainModule.GetType (typeName.Replace ('+', '/'));
 		}
 
 		public static bool Implements (this TypeReference self, string interfaceName, IMetadataResolver resolver)

src/Xamarin.Android.Build.Tasks/Utilities/MarshalMethodsClassifier.cs

@@ -109,7 +109,9 @@ public ConnectorInfo (string spec)
 
 				string fullTypeName = connectorSpec[1];
 				int comma = fullTypeName.IndexOf (',');
-				TypeName = fullTypeName.Substring (0, comma);
+
+				// Need to use IL convention, not Reflection convention
+				TypeName = fullTypeName.Substring (0, comma).Replace ('+', '/');
 				AssemblyName = AssemblyNameReference.Parse (fullTypeName.Substring (comma + 1).Trim ());
 			}
 		}