try {
      collection.add(sampleElement);
      fail("add succeeded on unmodifiable collection");
    } catch (UnsupportedOperationException expected) {
    }

    assertCollectionsAreEquivalent(copy, collection);

    try {
      collection.addAll(siblingCollection);
      fail("addAll succeeded on unmodifiable collection");
    } catch (UnsupportedOperationException expected) {
    }

    try {
      collection.add(sampleElement);
      fail("add succeeded on unmodifiable collection");
    } catch (UnsupportedOperationException expected) {
    }

    assertCollectionsAreEquivalent(copy, collection);

    try {
      collection.addAll(siblingCollection);
      fail("addAll succeeded on unmodifiable collection");
    } catch (UnsupportedOperationException expected) {
    }

      if (executed) {
        return;
      }
      executed = true;
      list = runnables;
      runnables = null; // allow GC to free listeners even if this stays around for a while.
    }
    // If we succeeded then list holds all the runnables we to execute. The pairs in the stack are
    // in the opposite order from how they were added so we need to reverse the list to fulfill our
    // contract.

       * other callers have added to it.
       *
       * This read is guaranteed to get us the right value because we only set this once (here).
       *
       * requireNonNull is safe because either our compareAndSet succeeded or it failed because
       * another thread did it for us.
       */
      seenExceptionsLocal = requireNonNull(seenExceptions);
    }
    return seenExceptionsLocal;
  }

   *     future
   * @param executor Executor to run the function in.
   * @return A future that holds result of the function (if the input succeeded) or the original
   *     input's failure (if not)
   */
  public final <T extends @Nullable Object> FluentFuture<T> transformAsync(
      AsyncFunction<? super V, T> function, Executor executor) {

          startDraining(true);
          continue DRAINING;
        } else if (result.isUnderflow()) {
          // If encoder underflows, it means either:
          // a) the final flush() succeeded; next drain (then done)
          // b) we encoded all of the input; next flush
          // c) we ran of out input to encode; next read more input
          if (doneEncoding) { // (a)
            doneFlushing = true;

          visitGenericArrayType((GenericArrayType) type);
        } else {
          throw new AssertionError("Unknown type: " + type);
        }
        succeeded = true;
      } finally {
        if (!succeeded) { // When the visitation failed, we don't want to ignore the second.
          visited.remove(type);
        }
      }
    }
  }

  void visitClass(Class<?> t) {}

        boolean expectedSuccess = fitsInInt(expectedResult);
        try {
          assertEquals(b + "^" + k, force32(expectedResult.intValue()), IntMath.checkedPow(b, k));
          assertTrue(b + "^" + k + " should have succeeded", expectedSuccess);
        } catch (ArithmeticException e) {
          assertFalse(b + "^" + k + " should have failed", expectedSuccess);
        }
      }
    }
  }

  @AndroidIncompatible // slow

  public static <V extends @Nullable Object> V getDone(Future<V> future) throws ExecutionException {
    /*
     * We throw IllegalStateException, since the call could succeed later. Perhaps we "should" throw
     * IllegalArgumentException, since the call could succeed with a different argument. Those
     * exceptions' docs suggest that either is acceptable. Google's Java Practices page recommends

  As there seemed to be no chance of getting her hands up to her
head, she tried to get her head down to them, and was delighted
to find that her neck would bend about easily in any direction,
like a serpent.  She had just succeeded in curving it down into a
graceful zigzag, and was going to dive in among the leaves, which
she found to be nothing but the tops of the trees under which she
had been wandering, when a sharp hiss made her draw back in a