code: public ExtendedRelation addRelationship(String baseTableName,
  			String relatedTableName, UserMappingTable userMappingTable,
  			String relationAuthor, String relationName) {
  		return addRelationship(baseTableName, relatedTableName,
  				userMappingTable,
  				buildRelationName(relationAuthor, relationName));
  	}
docs: Adds a relationship between the base and related table. Creates the user
  mapping table if needed.
  
  @param baseTableName
  base table name
  @param relatedTableName
  related table name
  @param userMappingTable
  user mapping table
  @param relationAuthor
  relation author
  @param relationName
  relation name
  @return The relationship that was added