====== Java Optional ======
  * [[http://www.oracle.com/technetwork/articles/java/java8-optional-2175753.html|Tired of Null Pointer Exceptions? Consider Using Java SE 8's Optional!]]
  * [[https://dzone.com/articles/optional-anti-patterns|Optional Anti-Patterns]]
  * [[https://www.youtube.com/watch?v=fBYhtvY19xA|Optional by Stuart Marks]]
  * [[https://medium.com/coding-with-clarity/understanding-the-optional-monad-in-java-8-e3000d85ffd2|Understanding the Optional Monad in Java 8 – Coding With Clarity]]
  * [[https://www.youtube.com/watch?v=Ej0sss6cq14|Optional - The Mother of All Bikesheds by Stuart Marks - YouTube]]
  * [[https://homoefficio.github.io/2019/10/03/Java-Optional-%EB%B0%94%EB%A5%B4%EA%B2%8C-%EC%93%B0%EA%B8%B0/|Java Optional 바르게 쓰기 - 뒤태지존의 끄적거림]]