public OptionalDouble minByDouble(DoubleUnaryOperator keyExtractor){
  double[] result=collect(null,null,null);
  return result[2] == 1 ? OptionalDouble.of(result[0]) : OptionalDouble.empty();
}

public OptionalDouble minByDouble ( DoubleUnaryOperator keyExtractor ) { double [ ] result = collect ( null , null , null ) ; return result [ 2 ] == 1 ? OptionalDouble . of ( result [ 0 ] ) : OptionalDouble . empty ( ) ; }
returns the minimum element of this stream according to the provided key extractor function . < p > this is a terminal operation .
