Listener close might get ahead of last event

      FunctionalMap.ReadOnlyMap<String, String> readOnlyMap = CreateFunctionalMaps.ro();
      FunctionalMap.WriteOnlyMap<String, String> writeOnlyMap = CreateFunctionalMaps.wo();
      FunctionalMap.ReadWriteMap<String, String> readWriteMap = CreateFunctionalMaps.rw();

      // `written` is a ReadEntryView of the written entry
      try(AutoCloseable handler = writeOnlyMap.listeners().onWrite(written ->
            System.out.printf("Written (via onWrite): %s%n", written.get()))) {
         Map<String, String> entries = new HashMap<>();
         entries.put("key1", "value1");
         entries.put("key2", "value2");

         writeOnlyMap.evalMany(entries, (v, writeView) -> writeView.set(v))
            .get(); // Wait for completable future
      }

      AutoCloseable writeCloseHandler = writeOnlyMap.listeners().add(new WriteListener<String, String>() {
         @Override
         public void onWrite(ReadEntryView<String, String> written) {
            System.out.printf("Written (via add): %s%n", written.get());
         }
      });

      CompletableFuture<Void> f0 = writeOnlyMap.eval("key1", view -> view.set("new-value1"));
      CompletableFuture<Void> f1 = f0.thenAccept(ignore ->
         writeOnlyMap.eval("key2", view -> view.set("new-value2")));
      CompletableFuture<Void> f2 = f1.thenAccept(ignore -> {
         try {
            writeCloseHandler.close();
         } catch (Exception e) {
            e.printStackTrace();  // TODO: Customise this generated block
         }
      });
      f2.get(); // Wait for completable future

Written (via onWrite): value1
Written (via onWrite): value2
Written (via add): new-value1