public void test_tryStartOperation_singleArg_delegatesToTwoArg() {
        // tryStartOperation(name) should delegate to tryStartOperation(name, null)
        final AtomicReference<String> passedData = new AtomicReference<>("NOT_NULL");
        final CoordinatorHelper helper = new CoordinatorHelper() {
            @Override
            public boolean tryStartOperation(final String operationName, final String data) {
                passedData.set(data);