@Override
  public final List<T> list(T filterConfig, String groupName) {
    CacheConfig currentPersistedConfig =
        persistenceService.getCacheConfig(
            AbstractConfiguration.isCluster(groupName) ? AbstractConfiguration.CLUSTER : groupName,
            true);
    return list(filterConfig, currentPersistedConfig);
  }
@param incoming the one that's about to be persisted
@param group the group name of the existing cache element
@param existing the existing cache element on another group
@throws IllegalArgumentException if the incoming CacheElement is not compatible with the
        existing

        Note: incoming and existing should have the same ID already
geode-core/src/main/java/org/apache/geode/management/internal/configuration/mutators/CacheConfigurationManager.java