SettableFuture<String> f = SettableFuture.create();
    Exception e = new IllegalArgumentException("foo not found");
    MockCallback callback = new MockCallback(e);
    addCallback(f, callback, directExecutor());
    f.setException(e);
  }

  public void testCancel() {
    SettableFuture<String> f = SettableFuture.create();
    FutureCallback<String> callback =
        new FutureCallback<String>() {

                        problems.add(new ModelProblemCollectorRequest(Severity.ERROR, Version.BASE)
                                .setMessage(e.getMessage())
                                .setException(e));
                    }
                    cache.put(value, c);
                }
                return c;
            }
            return value;
        };
    }

    /**
     * Gets the exceptions that occurred while building the dependency graph.
     *
     * @return the exceptions that occurred, never {@code null}
     */
    @Nonnull
    List<Exception> getExceptions();

    /**
     * Gets the root node of the dependency graph.
     *
     * @return the root node of the dependency graph or {@code null} if none
     */
    @Nullable
    Node getRoot();

    /**

    T fallbackResult;
    try {
      fallbackResult = doFallback(localFallback, castThrowable);
    } catch (Throwable t) {
      restoreInterruptIfIsInterruptedException(t);
      setException(t);
      return;
    } finally {
      exceptionType = null;
      fallback = null;
    }

    setResult(fallbackResult);
  }

  @Override
  @CheckForNull

                System.err.println("Missing: " + artifact);
            }
        }

        if (result.hasExceptions()) {
            for (Exception e : result.getExceptions()) {
                e.printStackTrace();
            }
        }
    }

    // ------------------------------------------------------------------------

    public boolean hasExceptions() {
        return exceptions != null && !exceptions.isEmpty();
    }

    public List<Exception> getExceptions() {
        return exceptions == null ? Collections.emptyList() : Collections.unmodifiableList(exceptions);
    }

    // ------------------------------------------------------------------------

    // ------------------------------------------------------------------------

    public boolean hasExceptions() {
        return exceptions != null && !exceptions.isEmpty();
    }

    public List<Exception> getExceptions() {
        return exceptions == null ? Collections.emptyList() : Collections.unmodifiableList(exceptions);
    }

    // ------------------------------------------------------------------------

    if (isDone()) {
      listener.execute();
    } else {
      listeners.add(listener);
    }
  }

  @CanIgnoreReturnValue
  protected boolean setException(Throwable throwable) {
    checkNotNull(throwable);
    if (!state.permitsPublicUserToTransitionTo(State.FAILURE)) {
      return false;
    }

    forceSetException(throwable);
    return true;
  }

      @Override
      public void run() {
        try {
          delegate.run();
        } catch (Throwable t) {
          // Any Exception is either a RuntimeException or sneaky checked exception.
          setException(t);
          throw t;
        }
      }

      @Override
      protected String pendingToString() {
        return "task=[" + delegate + "]";
      }
    }
  }

  /*

    @CanIgnoreReturnValue
    public boolean set(@CheckForNull V newValue) {
      return futureValue.set(newValue);
    }

    @CanIgnoreReturnValue
    public boolean setException(Throwable t) {
      return futureValue.setException(t);
    }

    private ListenableFuture<V> fullyFailedFuture(Throwable t) {
      return immediateFailedFuture(t);
    }

    @Override