[Xamarin.Android.Build.Tasks] require JDK 11 for API 31

API 31 builds fail when using JDK 1.8 with:

    /Library/Frameworks/Mono.framework/External/xbuild/Xamarin/Android/Xamarin.Android.Common.targets(1728,3):
    error JAVAC0000: java.lang.AssertionError: annotationType() : unrecognized Attribute name MODULE (class com.sun.tools.javac.util.SharedNameTable$NameImpl)

To solve this issue, we must require JDK 11 for API 31.

There are two code paths here for "legacy" Xamarin.Android and .NET 6.
Legacy is straightforward, as we already had a pattern for this.

In .NET 6, I checked the `$(TargetPlatformVersion)` property for now
and require JDK 11 in that case. When API 31 is stable, we can
probably remove this code and just set this value by default:

    <MinimumSupportedJavaVersion Condition=" '$(MinimumSupportedJavaVersion)' == '' ">11.0</MinimumSupportedJavaVersion>

* Add new `AssertTargetFrameworkVersionSupported()` method

In tests where it makes sense, I used a different
`$(TargetFrameworkVersion)` or just removed what was setting the
property entirely.

Other tests, I used a `AssertTargetFrameworkVersionSupported()` method
to `Assert.Ignore()` the test if it would not pass otherwise.

Author: jonathanpeppers

Documentation/release-notes/6084.md

@@ -0,0 +1,8 @@
+#### Application build and deployment
+
+- [GitHub Pull Request #6084](https://github.com/xamarin/xamarin-android/pull/6084):
+  Android API 31 and a `$(TargetFrameworkVersion)` of `v11.0.99`
+  requires JDK 11. This can be obtained manually by installing
+  [Microsoft OpenJDK 11][ms-openjdk].
+
+[ms-openjdk]: https://docs.microsoft.com/java/openjdk/download

src/Xamarin.Android.Build.Tasks/Microsoft.Android.Sdk/targets/Microsoft.Android.Sdk.Tooling.targets

@@ -23,6 +23,7 @@ called for "legacy" projects in Xamarin.Android.Legacy.targets.
         JavaSdkPath="$(_JavaSdkDirectory)"
         JavaToolExe="$(JavaToolExe)"
         JavacToolExe="$(JavacToolExe)"
+        TargetPlatformVersion="$(TargetPlatformVersion)"
         LatestSupportedJavaVersion="$(LatestSupportedJavaVersion)"
         MinimumSupportedJavaVersion="$(MinimumSupportedJavaVersion)">
       <Output TaskParameter="JdkVersion"                PropertyName="_JdkVersion" />

src/Xamarin.Android.Build.Tasks/Tasks/Legacy/ValidateJavaVersion.cs

@@ -50,13 +50,8 @@ protected override bool ValidateJava (string javaExe, Regex versionRegex)
 		Version GetJavaVersionForFramework ()
 		{
 			var apiLevel = MonoAndroidHelper.SupportedVersions.GetApiLevelFromFrameworkVersion (TargetFrameworkVersion);
-			if (apiLevel >= 30) {
-				// At present, it *looks like* API-R works with Build-tools r29, but
-				// historically API-X requires Build-tools rX, so if/when API-30
-				// requires Build-tools r30, it will require JDK11.
-				// return new Version (11, 0);
-				return new Version (1, 8);
-			}
+			if (apiLevel >= 31)
+				return new Version (11, 0);
 			if (apiLevel >= 24)
 				return new Version (1, 8);
 			else if (apiLevel == 23)

src/Xamarin.Android.Build.Tasks/Tasks/ValidateJavaVersion.cs

@@ -21,6 +21,8 @@ public class ValidateJavaVersion : AndroidTask
 
 		public string JavacToolExe { get; set; }
 
+		public string TargetPlatformVersion { get; set; }
+
 		[Required]
 		public string LatestSupportedJavaVersion { get; set; }
 
@@ -67,6 +69,9 @@ bool ValidateJava ()
 		protected virtual bool ValidateJava (string javaExe, Regex versionRegex)
 		{
 			var required = Version.Parse (MinimumSupportedJavaVersion);
+			if (Version.TryParse (TargetPlatformVersion, out var targetPlatformVersion) && targetPlatformVersion.Major >= 31) {
+				required = new Version (11, 0);
+			}
 			MinimumRequiredJdkVersion = required.ToString ();
 
 			try {

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/BuildTest.cs

@@ -48,6 +48,8 @@ public static string [] SupportedTargetFrameworks ()
 		[Test]
 		public void BuildBasicApplication ([ValueSource (nameof (SupportedTargetFrameworks))] string tfv, [Values (true, false)] bool isRelease)
 		{
+			AssertTargetFrameworkVersionSupported (tfv);
+
 			var proj = new XamarinAndroidApplicationProject {
 				IsRelease = isRelease,
 				TargetFrameworkVersion = tfv,
@@ -1143,8 +1145,6 @@ public void BuildMultiDexApplication ([Values ("dx", "d8")] string dexTool)
 			}
 
 			using (var b = CreateApkBuilder (Path.Combine ("temp", TestName), false, false)) {
-				proj.TargetFrameworkVersion = b.LatestTargetFrameworkVersion ();
-
 				string intermediateDir;
 				if (IsWindows && !Builder.UseDotNet) {
 					intermediateDir = Path.Combine (Root, b.ProjectDirectory, proj.IntermediateOutputPath, proj.TargetFrameworkAbbreviated);
@@ -2348,11 +2348,13 @@ public void CheckTargetFrameworkVersion ([Values (true, false)] bool isRelease)
 			proj.SetProperty ("AndroidUseLatestPlatformSdk", "False");
 			using (var builder = CreateApkBuilder ()) {
 				builder.GetTargetFrameworkVersionRange (out var _, out string firstFrameworkVersion, out var _, out string lastFrameworkVersion, out string[] _);
+				AssertTargetFrameworkVersionSupported (firstFrameworkVersion);
 				proj.SetProperty ("TargetFrameworkVersion", firstFrameworkVersion);
 				if (!Directory.Exists (Path.Combine (builder.FrameworkLibDirectory, firstFrameworkVersion)))
 					Assert.Ignore ("This is a Pull Request Build. Ignoring test.");
 				Assert.IsTrue (builder.Build (proj), "Build should have succeeded.");
 				Assert.IsTrue (StringAssertEx.ContainsText (builder.LastBuildOutput, $"Output Property: TargetFrameworkVersion={firstFrameworkVersion}"), $"TargetFrameworkVerson should be {firstFrameworkVersion}");
+				AssertTargetFrameworkVersionSupported (lastFrameworkVersion);
 				Assert.IsTrue (builder.Build (proj, parameters: new [] { $"TargetFrameworkVersion={lastFrameworkVersion}" }), "Build should have succeeded.");
 				Assert.IsTrue (StringAssertEx.ContainsText (builder.LastBuildOutput, $"Output Property: TargetFrameworkVersion={lastFrameworkVersion}"), $"TargetFrameworkVersion should be {lastFrameworkVersion}");
 			}

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/CodeBehindTests.cs

@@ -478,8 +478,6 @@ string[] GetBuildProperties (LocalBuilder builder, bool manyBuild, bool dtbBuild
 			var ret = new List <string> {
 				"AndroidGenerateLayoutBindings=true"
 			};
-			if (!Builder.UseDotNet)
-				ret.Add ("TargetFrameworkVersion=" + builder.LatestTargetFrameworkVersion ());
 			if (manyBuild)
 				ret.Add ("ForceParallelBuild=true");
 

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Tasks/ResolveSdksTaskTests.cs

@@ -21,7 +21,10 @@ public class ResolveSdksTaskTests : BaseTest {
 			new ApiInfo () { Id = "25", Level = 25, Name = "Nougat", FrameworkVersion = "v7.1",  Stable = true },
 			new ApiInfo () { Id = "26", Level = 26, Name = "Oreo", FrameworkVersion = "v8.0",  Stable = true  },
 			new ApiInfo () { Id = "27", Level = 27, Name = "Oreo", FrameworkVersion = "v8.1",  Stable = true  },
-			new ApiInfo () { Id = "P",  Level = 28, Name = "P",    FrameworkVersion = "v8.99", Stable = false },
+			new ApiInfo () { Id = "28", Level = 28, Name = "Pie",    FrameworkVersion = "v9.0", Stable = false },
+			new ApiInfo () { Id = "29", Level = 29, Name = "Android10", FrameworkVersion = "v10.0", Stable = false },
+			new ApiInfo () { Id = "30", Level = 30, Name = "Android11", FrameworkVersion = "v11.0", Stable = false },
+			new ApiInfo () { Id = "S",  Level = 31, Name = "S",         FrameworkVersion = "v11.0.99", Stable = false },
 			new ApiInfo () { Id = "Z",  Level = 127, Name = "Z",    FrameworkVersion = "v108.1.99", Stable = false },
 		};
 
@@ -35,9 +38,9 @@ public class ResolveSdksTaskTests : BaseTest {
 				/* jdk */ "1.8.0",
 				/* apis*/ apiInfoSelection,
 				/* useLatestAndroidSdk */ true,
-				/* targetFrameworkVersion */ "v8.99",
+				/* targetFrameworkVersion */ "v9.0",
 				/* expectedTaskResult */ true,
-				/* expectedTargetFramework */ "v8.99",
+				/* expectedTargetFramework */ "v9.0",
 				/* expectedError */ "",
 				/* expectedErrorMessage */ "",
 			},
@@ -101,9 +104,9 @@ public class ResolveSdksTaskTests : BaseTest {
 				/* jdk */ "1.8.0",
 				/* apis*/ apiInfoSelection,
 				/* useLatestAndroidSdk */ false,
-				/* targetFrameworkVersion */ "v8.99",
+				/* targetFrameworkVersion */ "v9.0",
 				/* expectedTaskResult */ true,
-				/* expectedTargetFramework */ "v8.99",
+				/* expectedTargetFramework */ "v9.0",
 				/* expectedError */ "",
 				/* expectedErrorMessage */ "",
 			},
@@ -151,6 +154,17 @@ public class ResolveSdksTaskTests : BaseTest {
 				/* expectedError */ "XA0001",
 				/* expectedErrorMessage */ "Unsupported or invalid $(TargetFrameworkVersion) value of 'v6.0'. Please update your Project Options.",
 			},
+			new object[] {
+				/* buildtools */   "30.0.0",
+				/* jdk */ "11.0",
+				/* apis*/ apiInfoSelection,
+				/* useLatestAndroidSdk */ false,
+				/* targetFrameworkVersion */ "v11.0.99",
+				/* expectedTaskResult */ true,
+				/* expectedTargetFramework */ "v11.0.99",
+				/* expectedError */ "",
+				/* expectedErrorMessage */ "",
+			},
 		};
 		#pragma warning restore 414
 		[Test]
@@ -184,7 +198,7 @@ public void UseLatestAndroidSdk (string buildtools, string jdk, ApiInfo[] apis,
 				JavaSdkPath = javaPath,
 				JavaToolExe = javaExe,
 				JavacToolExe = javacExe,
-				LatestSupportedJavaVersion = "1.8.0",
+				LatestSupportedJavaVersion = LatestSupportedJavaVersion,
 				MinimumSupportedJavaVersion = "1.7.0",
 			};
 			var androidTooling = new ResolveAndroidTooling {
@@ -429,6 +443,7 @@ public void LatestTFV_OldTargetSdkVersion ()
 			proj.TargetSdkVersion = "19";
 			using (var b = CreateApkBuilder ()) {
 				proj.TargetFrameworkVersion = b.LatestTargetFrameworkVersion ();
+				AssertTargetFrameworkVersionSupported (proj.TargetFrameworkVersion);
 				Assert.IsTrue (b.Build (proj), "Build should have succeeded.");
 			}
 		}

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/Utilities/BaseTest.cs

@@ -197,6 +197,16 @@ protected static void AssertAaptSupported (bool useAapt2)
 			}
 		}
 
+		protected static void AssertTargetFrameworkVersionSupported (string targetFrameworkVersion)
+		{
+			if (Builder.UseDotNet)
+				return; // N/A in .NET 6
+			if (!Version.TryParse (targetFrameworkVersion.TrimStart ('v'), out var version) || version <= new Version (11, 0))
+				return; // TFV is 11.0 or less
+			if (!TestEnvironment.IsUsingJdk11)
+				Assert.Ignore ("Test is only supported when using JDK 11.");
+		}
+
 		protected static void WaitFor(int milliseconds)
 		{
 			var pause = new ManualResetEvent(false);

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/XASdkTests.cs

@@ -556,6 +556,10 @@ public void XamarinLegacySdk ()
 			using var b = new Builder ();
 			var dotnetTargetFramework = "net6.0-android30.0";
 			var legacyTargetFrameworkVersion = b.LatestTargetFrameworkVersion ().TrimStart ('v');
+			// We need to replace 4.4, but not 11.0, for example
+			if (!legacyTargetFrameworkVersion.EndsWith (".0", StringComparison.Ordinal)) {
+				legacyTargetFrameworkVersion = legacyTargetFrameworkVersion.Replace (".", "");
+			}
 			var legacyTargetFramework = $"monoandroid{legacyTargetFrameworkVersion}";
 			proj.SetProperty ("TargetFramework",  value: "");
 			proj.SetProperty ("TargetFrameworks", value: $"{dotnetTargetFramework};{legacyTargetFramework}");

tests/MSBuildDeviceIntegration/Tests/DebuggingTest.cs

@@ -32,6 +32,8 @@ void SetTargetFrameworkAndManifest(XamarinAndroidApplicationProject proj, Builde
 				proj.TargetFrameworkVersion = "v11.0";
 			}
 
+			AssertTargetFrameworkVersionSupported (proj.TargetFrameworkVersion);
+
 			proj.AndroidManifest = $@"<?xml version=""1.0"" encoding=""utf-8""?>
 <manifest xmlns:android=""http://schemas.android.com/apk/res/android"" android:versionCode=""1"" android:versionName=""1.0"" package=""{proj.PackageName}"">
 	<uses-sdk android:minSdkVersion=""24"" android:targetSdkVersion=""{apiLevel}"" />