don't leak debugged process via cached toString() method in user data

java/debugger/impl/src/com/intellij/debugger/engine/DebugProcessImpl.java

@@ -775,6 +775,7 @@ public abstract class DebugProcessImpl implements DebugProcess {
         myReturnValueWatcher = null;
         myNodeRederersMap.clear();
         myRenderers.clear();
+        DebuggerUtils.cleanupAfterProcessFinish(this);
         myState.set(STATE_DETACHED);
         try {
           myDebugProcessDispatcher.getMulticaster().processDetached(this, closedByUser);

java/debugger/openapi/src/com/intellij/debugger/engine/DebuggerUtils.java

@@ -54,6 +54,10 @@ public abstract class DebuggerUtils {
       "byte", "short", "int", "long", "float", "double", "boolean", "char"
   ));
 
+  public static void cleanupAfterProcessFinish(DebugProcess debugProcess) {
+    debugProcess.putUserData(TO_STRING_METHOD_KEY, null);
+  }
+
   @NonNls
   public static String getValueAsString(final EvaluationContext evaluationContext, Value value) throws EvaluateException {
     try {