diff --git a/build-tools/gradle/gradle/wrapper/gradle-wrapper.properties b/build-tools/gradle/gradle/wrapper/gradle-wrapper.properties
index fae08049a..d6e308a63 100644
--- a/build-tools/gradle/gradle/wrapper/gradle-wrapper.properties
+++ b/build-tools/gradle/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.1.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.12-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
diff --git a/src/Java.Base/Java.Lang/StringBuffer.cs b/src/Java.Base/Java.Lang/StringBuffer.cs
index 13a798613..8488622b4 100644
--- a/src/Java.Base/Java.Lang/StringBuffer.cs
+++ b/src/Java.Base/Java.Lang/StringBuffer.cs
@@ -4,5 +4,15 @@
 
 namespace Java.Lang {
 	partial class StringBuffer : IEnumerable, IEnumerable<char> {
+
+#if JAVA_API_21
+		IAppendable? IAppendable.Append (char c) =>
+			Append (c);
+		IAppendable? IAppendable.Append (ICharSequence? s) =>
+			Append (s);
+		IAppendable? IAppendable.Append (ICharSequence? s, int a, int b) =>
+			Append (s, a, b);
+#endif  // JAVA_API_21
+
 	}
 }
diff --git a/src/Java.Base/Java.Lang/StringBuilder.cs b/src/Java.Base/Java.Lang/StringBuilder.cs
index 0eecdaa24..f71efa4df 100644
--- a/src/Java.Base/Java.Lang/StringBuilder.cs
+++ b/src/Java.Base/Java.Lang/StringBuilder.cs
@@ -4,5 +4,15 @@
 
 namespace Java.Lang {
 	partial class StringBuilder : IEnumerable, IEnumerable<char> {
+
+#if JAVA_API_21
+		IAppendable? IAppendable.Append (char c) =>
+			Append (c);
+		IAppendable? IAppendable.Append (ICharSequence? s) =>
+			Append (s);
+		IAppendable? IAppendable.Append (ICharSequence? s, int a, int b) =>
+			Append (s, a, b);
+#endif  // JAVA_API_21
+
 	}
 }
diff --git a/src/Java.Base/Java.Lang/Thread.cs b/src/Java.Base/Java.Lang/Thread.cs
new file mode 100644
index 000000000..d13a6bb4e
--- /dev/null
+++ b/src/Java.Base/Java.Lang/Thread.cs
@@ -0,0 +1,30 @@
+namespace Java.Lang {
+	partial class Thread {
+
+#if JAVA_API_21
+		partial interface IBuilder {
+			partial class IOfPlatformInvoker {
+				IBuilder? IBuilder.InheritInheritableThreadLocals (bool value) =>
+					InheritInheritableThreadLocals (value);
+				IBuilder? IBuilder.Name (string? name) =>
+					Name (name);
+				IBuilder? IBuilder.Name (string? name, long v) =>
+					Name (name, v);
+				IBuilder? IBuilder.UncaughtExceptionHandler (IUncaughtExceptionHandler? u) =>
+					UncaughtExceptionHandler (u);
+			}
+			partial class IOfVirtualInvoker {
+				IBuilder? IBuilder.InheritInheritableThreadLocals (bool value) =>
+					InheritInheritableThreadLocals (value);
+				IBuilder? IBuilder.Name (string? name) =>
+					Name (name);
+				IBuilder? IBuilder.Name (string? name, long v) =>
+					Name (name, v);
+				IBuilder? IBuilder.UncaughtExceptionHandler (IUncaughtExceptionHandler? u) =>
+					UncaughtExceptionHandler (u);
+			}
+		}
+#endif  // JAVA_API_21
+
+	}
+}
diff --git a/src/Xamarin.Android.Tools.Bytecode/Methods.cs b/src/Xamarin.Android.Tools.Bytecode/Methods.cs
index 6059b12eb..a0fdfba78 100644
--- a/src/Xamarin.Android.Tools.Bytecode/Methods.cs
+++ b/src/Xamarin.Android.Tools.Bytecode/Methods.cs
@@ -300,14 +300,16 @@ void UpdateParametersFromMethodParametersAttribute (ParameterInfo[] parameters)
 				 MethodParameterAccessFlags.Final | MethodParameterAccessFlags.Synthetic;
 			var pinfo = methodParams.ParameterInfo;
 			int startIndex = 0;
-			while (startIndex < pinfo.Count &&
-				   ((pinfo [startIndex].AccessFlags & OuterThis1) == OuterThis1 ||
-				    (pinfo [startIndex].AccessFlags & OuterThis2) == OuterThis2)) {
+			while (IsConstructor &&
+					startIndex < pinfo.Count &&
+					((pinfo [startIndex].AccessFlags & OuterThis1) == OuterThis1 ||
+					 (pinfo [startIndex].AccessFlags & OuterThis2) == OuterThis2)) {
 				startIndex++;
 			}
 			Debug.Assert (
 					parameters.Length == pinfo.Count - startIndex,
-					$"Unexpected number of method parameters in `{DeclaringType.FullJniName}.{Name}{Descriptor}`: expected {parameters.Length}, got {pinfo.Count - startIndex}");
+					$"Unexpected number of method parameters in `{DeclaringType.FullJniName}.{Name}{Descriptor}`: expected {parameters.Length}, got {pinfo.Count - startIndex}! " +
+					$"pinfo.Count={pinfo.Count}, startIndex={startIndex}, pinfo={string.Join (", ", pinfo.Select (p => p.ToString ()))}");
 			int end = Math.Min (parameters.Length, pinfo.Count - startIndex);
 			for (int i = 0; i < end; ++i) {
 				var p = pinfo [i + startIndex];