Optional nullable

Main.java

package com.ariesmcrae.combination.service;

import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Optional;
import java.util.stream.Collectors;

public class Main {

  public static void main(String... args) {
    List<String> adjustmentPlansWrapper = null;

    List<String> adjustmentPlans = Optional.ofNullable(adjustmentPlansWrapper)
        .orElse(Collections.emptyList())
        .stream()
        .parallel()
        .collect(Collectors.toList());

    System.out.println(adjustmentPlans);


    adjustmentPlansWrapper = Arrays.asList("a", "b");

    adjustmentPlans = Optional.ofNullable(adjustmentPlansWrapper)
        .orElse(Collections.emptyList())
        .stream()
        .parallel()
        .collect(Collectors.toList());

    System.out.println(adjustmentPlans);

  }

}

//Result:
//[]
//[a, b]