private static Iterable < String > head ( final Response origin , final int status , final CharSequence reason ) throws IOException { // @checkstyle MagicNumber (1 line) if ( status < 100 || status > 999 ) { throw new IllegalArgumentException ( String . format ( // @checkstyle LineLength (1 line) "according to RFC 7230 HTTP status code must have three digits: %d" , status ) ) ; } return new Concat <> ( Collections . singletonList ( String . format ( "HTTP/1.1 %d %s" , status , reason ) ) , new Filtered <> ( item -> ! item . startsWith ( "HTTP/" ) , origin . head ( ) ) ) ; }
Make head .