question: public Certificate engineGetCertificate ( String alias ) { if ( alias == null ) { throw new IllegalArgumentException ( "null alias passed to getCertificate." ) ; } Certificate c = ( Certificate ) certs . get ( alias ) ; if ( c == null ) { String id = ( String ) localIds . get ( alias ) ; if ( id != null ) { c = ( Certificate ) keyCerts . get ( id ) ; } else { c = ( Certificate ) keyCerts . get ( alias ) ; } } return c ; }
target:  simply return the cert for the private key