*/
  protected abstract Iterable<? extends Stimulus<E, ? super I>> getStimulusValues();

  /**
   * Returns a new target iterator each time it's called. This is the iterator you are trying to
   * test. This must return an Iterator that returns the expected elements passed to the constructor
   * in the given order. Warning: it is not enough to simply pull multiple iterators from the same

  private static final class Failure {
    static final Failure FALLBACK_INSTANCE =
        new Failure(
            new Throwable("Failure occurred while trying to finish a future.") {
              @Override
              public synchronized Throwable fillInStackTrace() {
                return this; // no stack trace
              }
            });

   */
  protected abstract Iterable<? extends Stimulus<E, ? super I>> getStimulusValues();

  /**
   * Returns a new target iterator each time it's called. This is the iterator you are trying to
   * test. This must return an Iterator that returns the expected elements passed to the constructor
   * in the given order. Warning: it is not enough to simply pull multiple iterators from the same

    } catch (Exception e) {
      throw new AssertionError(e); // only called if running on JDK7
    }
  }

  /**
   * Asserts that an exception was thrown when trying to close each of the given throwables and that
   * each such exception was suppressed because of the given thrown exception.
   */
  private void assertSuppressed(Suppression... expected) {

                     pass -XepCompilingTestOnlyCode, and that argument needs to
                     be passed as part of the same <arg> as -Xplugin:ErrorProne,
                     and I gave up trying to figure out how to do that for test
                     compilation only. -->
                <arg>-Xplugin:ErrorProne -Xep:NullArgumentForNonNullParameter:OFF -Xep:Java8ApiChecker:ERROR</arg>

    } catch (Exception e) {
      throw new AssertionError(e); // only called if running on JDK7
    }
  }

  /**
   * Asserts that an exception was thrown when trying to close each of the given throwables and that
   * each such exception was suppressed because of the given thrown exception.
   */
  private void assertSuppressed(Suppression... expected) {

              [INFO] Compile with -strict or with -logLevel set to TRACE or DEBUG to see all errors.

            Turning up the log level, we see that GWT is trying to compile classes from other
            packages, like RangeTest. The reason for this is that GWT doesn't distinguish between
            .java files in c.g.c.collect.Collect, a module that the c.g.c.base test module inherits,