@Override
    public Object load2(LoaderHelper helper) {
      if (helper.getArgument() instanceof String) {
        if (!CALLBACK_ARG.equals(helper.getArgument())) {
          fail("Expected " + helper.getArgument() + " to be " + CALLBACK_ARG);
        }
      } else {
        if (!helper.getKey().equals(ClientServerTestCase.NON_EXISTENT_KEY)) {
          fail("Expected callback arg to be " + CALLBACK_ARG + " but it was null");
        }
      }
      return super.load2(helper);
    }
Class <code>ClientServerGetAllDUnitTest</code> test client/server getAll.

@since GemFire 5.7
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/ClientServerGetAllDUnitTest.java