package Ġap pt ent ive . com . android . util Ċ Ċ @ Requires Opt In ( ĊĠĠĠ Ġmessage Ġ= Ġ" This Ġis Ġan Ġinternal ĠAPI Ġthat ĠAp pt ent ive Ġlibrary Ġuses , Ġplease Ġdon 't Ġrely Ġon Ġit ", ĊĠĠĠ Ġlevel Ġ= ĠRequires Opt In . Level . ERROR Ċ ) Ċ @ Retention ( Annotation Retention . BINARY ) Ċ @ Target ( ĊĠĠĠ ĠAnnotation Target . CLASS , ĊĠĠĠ ĠAnnotation Target . FUNCTION , ĊĠĠĠ ĠAnnotation Target . FIELD , ĊĠĠĠ ĠAnnotation Target . TYPE ALIAS , Ċ ) Ċ annotation Ġclass ĠInternal Use Only Ġ// ĠOpt - in Ġrequirement Ġannotation Ċ