derivedSuites.add(createSubsetSuite(parentBuilder, Bound.EXCLUSIVE, Bound.NO_BOUND));
      derivedSuites.add(createSubsetSuite(parentBuilder, Bound.EXCLUSIVE, Bound.EXCLUSIVE));
      derivedSuites.add(createSubsetSuite(parentBuilder, Bound.EXCLUSIVE, Bound.INCLUSIVE));
      derivedSuites.add(createSubsetSuite(parentBuilder, Bound.INCLUSIVE, Bound.INCLUSIVE));
    }

    }

    @Override
    public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
      return new NavigableElementSet<>(
          multiset().headMultiset(toElement, BoundType.forBoolean(inclusive)));
    }

    @Override
    public NavigableSet<E> tailSet(@ParametricNullness E fromElement, boolean inclusive) {
      return new NavigableElementSet<>(

      derivedSuites.add(createSubMultisetSuite(parentBuilder, Bound.INCLUSIVE, Bound.EXCLUSIVE));
      derivedSuites.add(createSubMultisetSuite(parentBuilder, Bound.INCLUSIVE, Bound.INCLUSIVE));
    }

    return derivedSuites;
  }

  private TestSuite createSubMultisetSuite(
      SortedMultisetTestSuiteBuilder<E> parentBuilder, Bound from, Bound to) {
    TestMultisetGenerator<E> delegate =

  OPEN(false),
  CLOSED(true);

  final boolean inclusive;

  BoundType(boolean inclusive) {
    this.inclusive = inclusive;
  }

  /** Returns the bound type corresponding to a boolean value for inclusivity. */
  static BoundType forBoolean(boolean inclusive) {
    return inclusive ? CLOSED : OPEN;
  }

      if (from == Bound.NO_BOUND && to == Bound.EXCLUSIVE) {
        return set.headSet(lastExclusive);
      } else if (from == Bound.INCLUSIVE && to == Bound.NO_BOUND) {
        return set.tailSet(firstInclusive);
      } else if (from == Bound.INCLUSIVE && to == Bound.EXCLUSIVE) {
        return set.subSet(firstInclusive, lastExclusive);
      } else {
        throw new IllegalArgumentException();
      }

    return subSet(fromElement, true, toElement, false);
  }

  @Override
  public NavigableSet<E> headSet(@ParametricNullness E toElement, boolean inclusive) {
    return delegate().headSet(toElement, inclusive);
  }

  /**
   * A sensible definition of {@link #headSet(Object)} in terms of the {@link #headSet(Object,

      for (List<Integer> contents : SAMPLE_INPUTS) {
        for (int i = 0; i < 10; i++) {
          for (boolean inclusive : ImmutableList.of(true, false)) {
            assertEquals(
                filter(createUnfiltered(contents).headSet(i, inclusive), EVEN),
                filter(createUnfiltered(contents), EVEN).headSet(i, inclusive));
          }
        }
      }
    }

    public void testNavigableTailSet() {

  OPEN(false),
  CLOSED(true);

  final boolean inclusive;

  BoundType(boolean inclusive) {
    this.inclusive = inclusive;
  }

  /** Returns the bound type corresponding to a boolean value for inclusivity. */
  static BoundType forBoolean(boolean inclusive) {
    return inclusive ? CLOSED : OPEN;
  }

      derivedSuites.add(createSubsetSuite(parentBuilder, Bound.EXCLUSIVE, Bound.NO_BOUND));
      derivedSuites.add(createSubsetSuite(parentBuilder, Bound.EXCLUSIVE, Bound.EXCLUSIVE));
      derivedSuites.add(createSubsetSuite(parentBuilder, Bound.EXCLUSIVE, Bound.INCLUSIVE));
      derivedSuites.add(createSubsetSuite(parentBuilder, Bound.INCLUSIVE, Bound.INCLUSIVE));
    }

      derivedSuites.add(createSubmapSuite(parentBuilder, Bound.EXCLUSIVE, Bound.NO_BOUND));
      derivedSuites.add(createSubmapSuite(parentBuilder, Bound.EXCLUSIVE, Bound.EXCLUSIVE));
      derivedSuites.add(createSubmapSuite(parentBuilder, Bound.EXCLUSIVE, Bound.INCLUSIVE));
      derivedSuites.add(createSubmapSuite(parentBuilder, Bound.INCLUSIVE, Bound.INCLUSIVE));
    }

    return derivedSuites;