code: public ExtendedRelation addAttributesRelationship(String baseTableName,
  			AttributesTable attributesTable, String mappingTableName) {
  		return addRelationship(baseTableName, attributesTable, mappingTableName);
  	}
docs: Adds an attributes relationship between the base table and user
  attributes related table. Creates a default user mapping table and the
  attributes table if needed.
  
  @param baseTableName
  base table name
  @param attributesTable
  user attributes table
  @param mappingTableName
  user mapping table name
  @return The relationship that was added
  @since 3.2.0