Properties testProp = new Properties();

    Map<String, String> result = Maps.fromProperties(testProp);
    assertTrue(result.isEmpty());
    testProp.setProperty("first", "true");

    result = Maps.fromProperties(testProp);
    assertThat(result.get("first")).isEqualTo("true");
    assertEquals(1, result.size());
    testProp.setProperty("second", "null");

            @Override
            protected String getIndexName() {
                return "fess_config.coordinator";
            }
        };

        helper.completeOperation("test_op");
        helper.completeOperation("test_op");
        assertEquals(2, callCount.get());
    }

    // ===================================================================================

  VerifyFDefEdges(fdef,
                  {{"feed1", "test_loop/Enter:0"},
                   {"test_loop/Enter:output:0", "test_loop/Merge:0"},
                   {"test_loop/Merge:output:0", "test_loop/Switch:0"},
                   {"test_loop/Switch:output_false:0", "test_loop/Exit:0"},
                   {"test_loop/Exit:output:0", "test_loop_exit"}},
                  {}, false);
}