Configuration configuration = getArchivaConfiguration().getConfiguration();
RepositoryGroupConfiguration repositoryGroupConfiguration =
configuration.getRepositoryGroupsAsMap().get( repositoryGroup.getId() );
configuration.removeRepositoryGroup( repositoryGroupConfiguration );
repositoryGroupConfiguration.setRepositories( repositoryGroup.getRepositories() );
repositoryGroupConfiguration.setMergedIndexPath( repositoryGroup.getMergedIndexPath() );
repositoryGroupConfiguration.setMergedIndexTtl( repositoryGroup.getMergedIndexTtl() );
configuration.addRepositoryGroup( repositoryGroupConfiguration );