title: CompletableFuture.exceptionally with executor
body: <p><a href="https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CompletableFuture.html#exceptionally-java.util.function.Function-" rel="noreferrer">CompletableFuture.exceptionally() method</a> takes a lambda, but there is no flavor of the method that takes a custom Executor, or even an "...Async" flavor of it.</p>
  
  <p>Which executor does exceptionally lambda run on? Would it be the same executor which ran the original CompletableFuture which threw the exception? Or (I would be surprised if this is the case) is it the commonPool ?</p>