code: private HazelcastInstance getOrCreateByInstanceName(String instanceName) {
          HazelcastInstance instance = Hazelcast.getHazelcastInstanceByName(instanceName);
          if (instance == null) {
              Config config = getDefaultConfig();
              config.setInstanceName(instanceName);
              instance = Hazelcast.getOrCreateHazelcastInstance(config);
          }
          return instance;
      }
docs: Gets an existing {@link HazelcastInstance} by {@code instanceName} or,
  if not found, creates a new {@link HazelcastInstance} with the default
  configuration and given {@code instanceName}.
  
  @param instanceName name to lookup an existing {@link HazelcastInstance}
  or to create a new one
  @return a {@link HazelcastInstance} with the given {@code instanceName}