[Dubbo-619] Fix consumer will generate wrong stackTrace (#2956)

* [Dubbo-619] Fix consumer will generate wrong stackTrace when provider throws exception with empty stackTrace

* add license

dubbo-rpc/dubbo-rpc-api/src/main/java/org/apache/dubbo/rpc/RpcResult.java

@@ -16,6 +16,8 @@
  */
 package org.apache.dubbo.rpc;
 
+import java.lang.reflect.Field;
+
 /**
  * RPC Result.
  *
@@ -39,6 +41,23 @@ public RpcResult(Throwable exception) {
     @Override
     public Object recreate() throws Throwable {
         if (exception != null) {
+            // fix issue#619
+            try {
+                // get Throwable class
+                Class clazz = exception.getClass();
+                while (!clazz.getName().equals(Throwable.class.getName())) {
+                    clazz = clazz.getSuperclass();
+                }
+                // get stackTrace value
+                Field stackTraceField = clazz.getDeclaredField("stackTrace");
+                stackTraceField.setAccessible(true);
+                Object stackTrace = stackTraceField.get(exception);
+                if (stackTrace == null) {
+                    exception.setStackTrace(new StackTraceElement[0]);
+                }
+            } catch (Exception e) {
+                // ignore
+            }
             throw exception;
         }
         return result;

dubbo-rpc/dubbo-rpc-api/src/test/java/org/apache/dubbo/rpc/RpcResultTest.java

@@ -0,0 +1,77 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.dubbo.rpc;
+
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import static org.junit.Assert.fail;
+
+public class RpcResultTest {
+    @Test
+    public void testRecreateWithNormalException() {
+        NullPointerException npe = new NullPointerException();
+        RpcResult rpcResult = new RpcResult(npe);
+        try {
+            rpcResult.recreate();
+            fail();
+        } catch (Throwable throwable) {
+            StackTraceElement[] stackTrace = throwable.getStackTrace();
+            Assert.assertNotNull(stackTrace);
+            Assert.assertTrue(stackTrace.length > 1);
+        }
+    }
+
+    /**
+     * please run this test in Run mode
+     */
+    @Test
+    public void testRecreateWithEmptyStackTraceException() {
+        // begin to construct a NullPointerException with empty stackTrace
+        Throwable throwable = null;
+        Long begin = System.currentTimeMillis();
+        while (System.currentTimeMillis() - begin < 60000) {
+            try {
+                ((Object) null).getClass();
+            } catch (Exception e) {
+                if (e.getStackTrace().length == 0) {
+                    throwable = e;
+                    break;
+                }
+            }
+        }
+        /**
+         * may be there is -XX:-OmitStackTraceInFastThrow or run in Debug mode
+         */
+        if (throwable == null) {
+            System.out.println("###testRecreateWithEmptyStackTraceException fail to construct NPE");
+            return;
+        }
+        // end construct a NullPointerException with empty stackTrace
+
+        RpcResult rpcResult = new RpcResult(throwable);
+        try {
+            rpcResult.recreate();
+            fail();
+        } catch (Throwable t) {
+            StackTraceElement[] stackTrace = t.getStackTrace();
+            Assert.assertNotNull(stackTrace);
+            Assert.assertTrue(stackTrace.length == 0);
+        }
+    }
+}