question: public String generateBearerToken ( String email , String username , Map < String , String > payload ) { String token = tokenGenerator . generate ( ) ; Map < String , String > payloadCopy = payload == null ? new HashMap ( ) : new HashMap ( payload ) ; payloadCopy . put ( "email" , email ) ; payloadCopy . put ( "username" , username ) ; payloadCopy . put ( "creation.time" , Long . toString ( System . currentTimeMillis ( ) ) ) ; tokenMap . put ( token , payloadCopy ) ; return token ; }
target:  Generate new token for given user.