public SplitBrainMergePolicy getMergePolicy(String className) {
        if (className == null) {
            throw new InvalidConfigurationException("Class name is mandatory!");
        }
        return getOrPutIfAbsent(mergePolicyMap, className, policyConstructorFunction);
    }
@Test
    public void getMergePolicy_withNullPolicy() {
        assertThatThrownBy(() -> mergePolicyProvider.getMergePolicy(null))
                .isInstanceOf(InvalidConfigurationException.class);
    }