Rpc future doesn't complete when transformer fails

@Test
public void testDeadlock() throws Exception {
    // when rpc is successful, but transformer fails for some reason
    final MessageTransformer<NetconfMessage> failingTransformer = mock(MessageTransformer.class);
    final RemoteDeviceCommunicator<NetconfMessage> communicatorMock = mock(RemoteDeviceCommunicator.class);
    final NetconfMessage msg = null;
    final RpcResult<NetconfMessage> result = RpcResultBuilder.success(msg).build();
    when(communicatorMock.sendRequest(any(), any())).thenReturn(Futures.immediateFuture(result));
    when(failingTransformer.toRpcResult(any(), any())).thenThrow(new RuntimeException("FAIL"));
    final NetconfDeviceRpc rpc = new NetconfDeviceRpc(SCHEMA_CONTEXT, communicatorMock, failingTransformer);
    // then guava logs and swallow exception and future never completes
    rpc.invokeRpc(path, null).get();
}