OptionalLolz.java

import java.util.Optional;
import java.util.function.Function;

class Main {
  public static void main(String[] args) {
    Optional<String> o = Optional.of("foo");
    Function<String, String> f = s -> null;
    Function<String, String> g = String::valueOf;
    
    //lawless lolz
    System.out.println(    o.map(g.compose(f))   ); //Optional[null]
    System.out.println(    o.map(f).map(g)       ); //Optional.empty
    
    //This is because
    System.out.println(    o.map(f)              ); //Optional.empty
    
    //Once again for clarity
    System.out.println(    o.map(s -> null)      ); //Optional.empty
    
    //And now for more lolz
    System.out.println(    o.flatMap(s -> null)  ); //throws NullPointerException
  }
}

FWIW, we tried this (failed) experiment about 12 years ago. The correct solution is to assume that null does not exist, at all.