title: mock instance is null after @Mock annotation
body: <p>I try to run this test:</p>
  
  <pre><code>    @Mock IRoutingObjHttpClient routingClientMock;
      @Mock IRoutingResponseRepository routingResponseRepositoryMock;
  
  
      @Test
      public void testSendRoutingRequest() throws Exception {
          CompleteRoutingResponse completeRoutingResponse = new CompleteRoutingResponse();
          completeRoutingResponse.regression_latencyMillis = 500L;
  
          Mockito.when(routingClientMock.sendRoutingRequest(any(RoutingRequest.class))).thenReturn(completeRoutingResponse);
  
          RoutingObjHttpClientWithReRun routingObjHttpClientWithReRun = new RoutingObjHttpClientWithReRun
                  (routingClientMock, routingResponseRepositoryMock);
  
  ...
      }
  </code></pre>
  
  <p>but I get NullPointerException for:</p>
  
  <p><code>Mockito.when(routingClientMock.</code></p>
  
  <p>what am i missing?</p>