question: private boolean addGroupToGroup ( String tenantName , PrincipalId groupId , String groupName ) throws Exception { try { ValidateUtil . validateNotEmpty ( tenantName , "Tenant name" ) ; ValidateUtil . validateNotNull ( groupId , "Group ID" ) ; ValidateUtil . validateNotEmpty ( groupName , "Group name" ) ; TenantInformation tenantInfo = findTenant ( tenantName ) ; ServerUtils . validateNotNullTenant ( tenantInfo , tenantName ) ; ISystemDomainIdentityProvider provider = tenantInfo . findSystemProvider ( ) ; ServerUtils . validateNotNullSystemIdp ( provider , tenantName ) ; if ( provider . findGroup ( groupId ) == null ) { Group group = findGroup ( tenantName , groupId ) ; if ( group != null ) { validateObjectIdNotNull ( group ) ; PrincipalId newGroupId = getFspIdForSystemDomain ( provider , group ) ; return provider . addGroupToGroup ( newGroupId , groupName ) ; } } return provider . addGroupToGroup ( groupId , groupName ) ; } catch ( Exception ex ) { logger . error ( String . format ( "Failed to add group [%s@%s] to group [%s] in tenant [%s]" , groupId != null ? groupId . getName ( ) : "null" , groupId != null ? groupId . getDomain ( ) : "null" , groupName , tenantName ) ) ; throw ex ; } }
target:  Adds a security group to another in the tenant's system domain. Applies to system provider only. For external provider, we have read privilege only. If the group is already exist, nothing is changed.