gets the attribute that is going to be indexed . if no attribute is set , null is returned . concode_field_sep boolean ordered concode_elem_sep MapIndexConfigReadOnly readOnly concode_elem_sep String attribute concode_field_sep MapIndexConfig setOrdered concode_elem_sep MapIndexConfig setAttribute concode_elem_sep String toString concode_elem_sep boolean isOrdered concode_elem_sep MapIndexConfigReadOnly getAsReadOnly
String function ( ) { return attribute ; }