code: @CheckResult
      @NonNull
      public static Condition observableCondition(@NonNull Observable<Boolean> observable) {
          return new ObservableCondition(observable);
      }
docs: Creates a {@link Condition} that derives is value from the latest value emitted by the specified {@link
  Observable}. Errors sent by the observable are ignored, but it's recommended not to supply an observable that
  is capable of errors or completion.