<!--- The issue this PR addresses -->
<!-- Fixes #? -->

### Context
<!--- Why do you believe many users will benefit from this change? -->
<!--- Link to relevant issues or forum discussions here -->

### Contributor Checklist
- [ ] [Review Contribution Guidelines](https://github.com/gradle/gradle/blob/master/CONTRIBUTING.md).

          required: true
        - label: >
            I have read and understood
            [Guava's philosophy](https://github.com/google/guava/wiki/PhilosophyExplained), and
            I strongly believe that this proposal aligns with it.
          required: true
        - label: >
            I have visited the [idea graveyard](https://github.com/google/guava/wiki/IdeaGraveyard),

          required: true
        - label: >
            I have read and understood
            [Guava's philosophy](https://github.com/google/guava/wiki/PhilosophyExplained), and
            I strongly believe that this proposal aligns with it.

              <extraJvmArgs>-Dgwt.watchFileChanges=false</extraJvmArgs>
            </configuration>
          </execution>
          <!--
            GWT issues some scary warnings while running tests, but I believe they are harmless.
            Let's take the warnings for one module, c.g.c.base.testModule, as an example:

              [INFO] Validating units:

and then take a look at the
[issues with the "contributions welcome" label](https://github.com/tensorflow/tensorflow/labels/stat%3Acontributions%20welcome).
These are issues that we believe are particularly well suited for outside
contributions, often because we probably won't get to them right now. If you
decide to start on an issue, leave a comment so that other people know that

    if (cause instanceof Error) {
      throw new ExecutionError((Error) cause);
    }
    /*
     * It's an Exception. (Or it's a non-Error, non-Exception Throwable. From my survey of such
     * classes, I believe that most users intended to extend Exception, so we'll treat it like an
     * Exception.)
     */
    throw new UncheckedExecutionException(cause);
  }

  /*

      requireNonNull(impl);
      requireNonNull(other.impl);
      /*
       * For discussion of requireNonNull, see the comment on the field.
       *
       * (And I don't believe there's any situation in which we call x.combine(y) when x is a plain
       * ImmutableSet.Builder but y is an ImmutableSortedSet.Builder (or vice versa). Certainly

        int hash = map.hash(key);
        Object value = new Object();

        ReferenceEntry<Object, Object> entry = createDummyEntry(key, hash, value, null);
        // must recordRead for drainRecencyQueue to believe this entry is live
        segment.recordWrite(entry, 1, map.ticker.read());
        writeOrder.add(entry);
        readOrder.add(entry);
      }

        int hash = map.hash(key);
        Object value = new Object();

        ReferenceEntry<Object, Object> entry = createDummyEntry(key, hash, value, null);
        // must recordRead for drainRecencyQueue to believe this entry is live
        segment.recordWrite(entry, 1, map.ticker.read());
        writeOrder.add(entry);
        readOrder.add(entry);
      }

   * {@link TreeSet} or the {@link Map#keySet} of an {@code IdentityHashMap}.
   *
   * <p><b>Note:</b> The returned view performs slightly better when {@code set1} is the smaller of
   * the two sets. If you have reason to believe one of your sets will generally be smaller than the
   * other, pass it first. Unfortunately, since this method sets the generic type of the returned