returns this chat as a groupchat . before invoking this method , check whether this chat is actually a group chat by calling chat #isgroupchat . concode_field_sep String firstName concode_elem_sep String lastName concode_elem_sep int id concode_elem_sep String title concode_elem_sep String username concode_field_sep int getId concode_elem_sep String toString concode_elem_sep boolean isUser concode_elem_sep boolean isGroupChat concode_elem_sep User asUser
GroupChat function ( ) { return new GroupChat ( id , title ) ; }