private static List < DAType > computeExtendedInterfaces ( List < DAInterface > interfaces ) { Optional < DAType > functionInterface = from ( interfaces ) . filter ( DAInterfacePredicates . isGuavaFunction ( ) ) . transform ( toDAType ( ) ) . filter ( notNull ( ) ) . first ( ) ; if ( functionInterface . isPresent ( ) ) { return Collections . singletonList ( functionInterface . get ( ) ) ; } return Collections . emptyList ( ) ; }
The only interface that can be extended by the Mapper interface is Guava s Function interface .