code: public Object getMergePolicy(String className) {
          if (className == null) {
              throw new InvalidConfigurationException("Class name is mandatory!");
          }
          try {
              return policyProvider.getMergePolicy(className);
          } catch (InvalidConfigurationException e) {
              return getOrPutIfAbsent(mergePolicyMap, className, policyConstructorFunction);
          }
      }
docs: Returns an instance of a merge policy by its classname.
  <p>
  First tries to resolve the classname as {@link SplitBrainMergePolicy},
  then as {@link com.hazelcast.cache.CacheMergePolicy}.
  <p>
  If no merge policy matches an {@link InvalidConfigurationException} is thrown.
  
  @param className the classname of the given merge policy
  @return an instance of the merge policy class
  @throws InvalidConfigurationException if no matching merge policy class was found