Optionally append java stack trace

src/Mono.Android/Android.Runtime/AndroidRuntime.cs

@@ -79,7 +79,7 @@ public override void RaisePendingException (Exception pendingException)
 		{
 			var je  = pendingException as JavaProxyThrowable;
 			if (je == null) {
-				je  = JavaProxyThrowable.Create (pendingException);
+				je  = JavaProxyThrowable.Create (pendingException, appendJavaStackTrace: true);
 			}
 			var r = new JniObjectReference (je.Handle);
 			JniEnvironment.Exceptions.Throw (r);

src/Mono.Android/Android.Runtime/JavaProxyThrowable.cs

@@ -16,7 +16,7 @@ sealed class JavaProxyThrowable : Java.Lang.Error {
 			InnerException  = innerException;
 		}
 
-		public static JavaProxyThrowable Create (Exception? innerException)
+		public static JavaProxyThrowable Create (Exception? innerException, bool appendJavaStackTrace = false)
 		{
 			if (innerException == null) {
 				throw new ArgumentNullException (nameof (innerException));
@@ -25,7 +25,7 @@ public static JavaProxyThrowable Create (Exception? innerException)
 			var proxy = new JavaProxyThrowable (innerException.Message, innerException);
 
 			try {
-				proxy.TranslateStackTrace ();
+				proxy.TranslateStackTrace (appendJavaStackTrace);
 			} catch {
 				// We shouldn't throw here, just try to do the best we can do
 				proxy = new JavaProxyThrowable (innerException.ToString (), innerException);
@@ -34,15 +34,25 @@ public static JavaProxyThrowable Create (Exception? innerException)
 			return proxy;
 		}
 
-		void TranslateStackTrace ()
+		void TranslateStackTrace (bool appendJavaStackTrace)
 		{
 			var trace = new StackTrace (InnerException, fNeedFileInfo: true);
 			if (trace.FrameCount <= 0) {
 				return;
 			}
 
+			StackTraceElement[]? javaTrace = null;
+			if (appendJavaStackTrace) {
+				try {
+					javaTrace = Java.Lang.Thread.CurrentThread ()?.GetStackTrace ();
+				} catch {
+					// Ignore
+				}
+			}
+
 			StackFrame[] frames = trace.GetFrames ();
-			StackTraceElement[] elements = new StackTraceElement[frames.Length];
+			int nElements = frames.Length + (javaTrace?.Length ?? 0);
+			StackTraceElement[] elements = new StackTraceElement[nElements];
 
 			for (int i = 0; i < frames.Length; i++) {
 				StackFrame managedFrame = frames[i];
@@ -58,6 +68,12 @@ void TranslateStackTrace ()
 				elements[i] = throwableFrame;
 			}
 
+			if (javaTrace != null) {
+				for (int i = frames.Length; i < nElements; i++) {
+					elements[i] = javaTrace[i - frames.Length];
+				}
+			}
+
 			SetStackTrace (elements);
 		}
 	}

tests/Mono.Android-Tests/System/ExceptionTest.cs

@@ -47,7 +47,7 @@ void CompareStackTraces (Exception ex, Java.Lang.Throwable throwable)
 			StackFrame[] managedFrames = managedTrace.GetFrames ();
 			Java.Lang.StackTraceElement[] javaFrames = throwable.GetStackTrace ();
 
-			Assert.AreEqual (managedFrames.Length, javaFrames.Length, "Java and managed stack traces have a different number of frames");
+			Assert.IsTrue (managedFrames.Length <= javaFrames.Length, "Java and managed stack traces have a different number of frames");
 			for (int i = 0; i < managedFrames.Length; i++) {
 				var mf = managedFrames[i];
 				var jf = javaFrames[i];