[TrimmableTypeMap] Skip UCO constructor generation for abstract types (#11461)

* Skip UCO constructor generation for abstract types

Abstract types are never directly instantiated from Java — the ACW
constructor's getClass() guard prevents activation. Generating UCO
constructor wrappers for them is dead code and fails when the managed
constructor is protected (which is legitimate for abstract types).

This fixes XAGTT7009 errors when using the trimmable type map with
abstract types like MAUI's CellAdapter that have protected constructors.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Assisted-by: Claude:claude-opus-4.6-1m

* Add test: abstract type with protected ctor builds with trimmable typemap

Verifies that abstract Java peer types with protected constructors do not
cause XAGTT7009 when using _AndroidTypeMapImplementation=trimmable.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Assisted-by: Claude:claude-opus-4.6-1m

* Add unit test: abstract type skips UCO constructor generation

Verifies that BuildUcoConstructors produces no UCO constructors for
abstract types, even when the Java constructor has SuperArgumentsString
and no matching public managed constructor exists. This complements
the existing Build_ExportConstructorWithoutMatchingManagedCtor_Throws
test which covers the concrete type case.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Assisted-by: Claude:claude-opus-4.6-1m

* Add IgnoreUnsupportedConfiguration guard to NativeAOT integration test

Addresses Copilot review feedback: the test hard-codes NativeAOT without
the IgnoreUnsupportedConfiguration guard, which can cause failures in
environments where NativeAOT builds are skipped.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Assisted-by: Claude:claude-opus-4.6-1m

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Šimon Rozsíval <simon@rozsival.com>

Author: 3 people

src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/ModelBuilder.cs

@@ -356,6 +356,13 @@ static void BuildUcoConstructors (JavaPeerInfo peer, JavaPeerProxyData proxy)
 			return;
 		}
 
+		// Abstract types are never directly instantiated from Java — the ACW
+		// constructor's getClass() guard prevents activation. Skip generating
+		// UCO constructor wrappers for them.
+		if (peer.IsAbstract) {
+			return;
+		}
+
 		foreach (var ctor in peer.JavaConstructors) {
 			if (ctor.SuperArgumentsString != null && !ctor.HasMatchingManagedCtor) {
 				throw new InvalidOperationException (

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

@@ -394,5 +394,36 @@ class ExportShapes : Java.Lang.Object {
 				"assembly or the user's [Export] source. Offending warning lines:\n  " +
 				string.Join ("\n  ", offending));
 		}
+
+		[Test]
+		public void Build_WithTrimmableTypeMap_AbstractTypeWithProtectedCtor_Succeeds ()
+		{
+			if (IgnoreUnsupportedConfiguration (AndroidRuntime.NativeAOT, release: true)) {
+				return;
+			}
+
+			var proj = new XamarinAndroidApplicationProject {
+				IsRelease = true,
+			};
+			proj.SetRuntime (AndroidRuntime.NativeAOT);
+			proj.SetProperty ("_AndroidTypeMapImplementation", "trimmable");
+			proj.Sources.Add (new BuildItem.Source ("AbstractProvider.cs") {
+				TextContent = () => @"
+namespace UnnamedProject {
+	public abstract class AbstractProvider : Java.Lang.Object {
+		protected AbstractProvider (Android.Content.Context context) { }
+		public abstract string GetData ();
+	}
+
+	public class ConcreteProvider : AbstractProvider {
+		public ConcreteProvider (Android.Content.Context context) : base (context) { }
+		public override string GetData () => ""hello"";
+	}
+}"
+			});
+
+			using var builder = CreateApkBuilder ();
+			Assert.IsTrue (builder.Build (proj), "Build should have succeeded — abstract types with protected ctors should not cause XAGTT7009.");
+		}
 	}
 }

tests/Microsoft.Android.Sdk.TrimmableTypeMap.Tests/Generator/TypeMapModelBuilderTests.cs

@@ -1369,6 +1369,26 @@ public void Build_ExportConstructorWithoutMatchingManagedCtor_Throws ()
 			Assert.Contains ("no matching user-visible managed constructor", ex.Message);
 			Assert.Contains ("MyApp.MissingCtor", ex.Message);
 		}
+
+		[Fact]
+		public void Build_AbstractTypeWithProtectedCtor_NoUcoConstructors ()
+		{
+			var peer = MakeAcwPeer ("my/app/AbstractAdapter", "MyApp.AbstractAdapter", "App") with {
+				IsAbstract = true,
+				JavaConstructors = new List<JavaConstructorInfo> {
+					new JavaConstructorInfo {
+						ConstructorIndex = 0,
+						JniSignature = "(Landroid/content/Context;)V",
+						HasMatchingManagedCtor = false,
+						SuperArgumentsString = "p0",
+					},
+				},
+			};
+			var model = BuildModel (new [] { peer });
+			var proxy = model.ProxyTypes.FirstOrDefault (p => p.TypeName.Contains ("AbstractAdapter"));
+			Assert.NotNull (proxy);
+			Assert.Empty (proxy.UcoConstructors);
+		}
 	}
 
 	public class NativeRegistrations