Nullify deleted global refs to force recreation.

src/org_pEp_jniadapter_AbstractEngine.cc

@@ -198,11 +198,11 @@ extern "C" {
         PEP_STATUS status = PEP_STATUS_OK;
 
         #ifdef DISABLE_SYNC
-                _messageToSend = messageToSend;
+           _messageToSend = messageToSend;
-                session();
+           session();
                 
         #else 
-                startup<JNISync>(messageToSend, notifyHandshake, o, &JNISync::startup_sync, &JNISync::shutdown_sync);
+            startup<JNISync>(messageToSend, notifyHandshake, o, &JNISync::startup_sync, &JNISync::shutdown_sync);
         #endif
     }
 
@@ -218,6 +218,11 @@ extern "C" {
         env->DeleteGlobalRef(engineClass);
         env->DeleteGlobalRef(obj);
 
+        identityClass = NULL;
+        signalClass = NULL;
+        engineClass = NULL;
+        obj = NULL;
+
         session(pEp::Adapter::release);
         delete o;
     }