question: public static < T extends Enum < T > > T forKey ( String key , Map < String , T > mapping , Class < T > enumeration ) { T t = mapping . get ( key ) ; if ( t != null ) { return t ; } throw new IllegalArgumentException ( "Not an alternate key for " + enumeration . toString ( ) + ": " + key ) ; }
target:  Boilerplate method to retrieve an enum method via an arbitrary key, rather than just the enum value.