},
            directExecutor());
    try {
      getDone(chainedFuture);
      fail();
    } catch (ExecutionException expected) {
      NullPointerException cause = (NullPointerException) expected.getCause();
      assertThat(cause)
          .hasMessageThat()
          .contains(
              "AsyncFunction.apply returned null instead of a Future. "

            },
            directExecutor());
    try {
      getDone(chainedFuture);
      fail();
    } catch (ExecutionException expected) {
      NullPointerException cause = (NullPointerException) expected.getCause();
      assertThat(cause)
          .hasMessageThat()
          .contains(
              "AsyncFunction.apply returned null instead of a Future. "

        return lockedGetOrLoad(key, hash, loader);
      } catch (ExecutionException ee) {
        Throwable cause = ee.getCause();
        if (cause instanceof Error) {
          throw new ExecutionError((Error) cause);
        } else if (cause instanceof RuntimeException) {
          throw new UncheckedExecutionException(cause);
        }
        throw ee;
      } finally {
        postReadCleanup();
      }
    }

   *
   * @param exceptionType the exception type that triggers use of {@code fallback}. The exception
   *     type is matched against this step's exception. "This step's exception" means the cause of
   *     the {@link ExecutionException} thrown by {@link Future#get()} on the {@link Future}
   *     underlying this step or, if {@code get()} throws a different kind of exception, that

     * expected</i>, but not absolutely required, to have the following properties:
     *
     * <ul>
     *   <li>Its execution does not cause any observable side effects.
     *   <li>The computation is <i>consistent with equals</i>; that is, {@link Objects#equal
     *       Objects.equal}{@code (k1, k2) &&} {@link Objects#equal}{@code (v1, v2)} implies that

     * expected</i>, but not absolutely required, to have the following properties:
     *
     * <ul>
     *   <li>Its execution does not cause any observable side effects.
     *   <li>The computation is <i>consistent with equals</i>; that is, {@link Objects#equal
     *       Objects.equal}{@code (k1, k2) &&} {@link Objects#equal}{@code (v1, v2)} implies that

        return lockedGetOrLoad(key, hash, loader);
      } catch (ExecutionException ee) {
        Throwable cause = ee.getCause();
        if (cause instanceof Error) {
          throw new ExecutionError((Error) cause);
        } else if (cause instanceof RuntimeException) {
          throw new UncheckedExecutionException(cause);
        }
        throw ee;
      } finally {
        postReadCleanup();
      }
    }

   *
   * @param exceptionType the exception type that triggers use of {@code fallback}. The exception
   *     type is matched against this step's exception. "This step's exception" means the cause of
   *     the {@link ExecutionException} thrown by {@link Future#get()} on the {@link Future}
   *     underlying this step or, if {@code get()} throws a different kind of exception, that