code: private InvocationHandlerAdapter getInvocationHandlerAdapter(Object instance) {
          if (instance == null) {
              return null;
          }
  
          return mocks.get(instance);
      }
docs: Get the {@link InvocationHandlerAdapter} registered for a mock.
  
  @param instance instance that might be mocked
  
  @return adapter for this mock, or {@code null} if instance is not mocked