}

  public void testPowerSetShowOff() {
    Set<Object> zero = ImmutableSet.of();
    Set<Set<Object>> one = powerSet(zero);
    Set<Set<Set<Object>>> two = powerSet(one);
    Set<Set<Set<Set<Object>>>> four = powerSet(two);
    Set<Set<Set<Set<Set<Object>>>>> sixteen = powerSet(four);
    Set<Set<Set<Set<Set<Set<Object>>>>>> sixtyFiveThousandish = powerSet(sixteen);

  }

  public void testEmpty_comparator() {
    SortedSet<String> set = of();
    assertSame(Ordering.natural(), set.comparator());
  }

  public void testEmpty_headSet() {
    SortedSet<String> set = of();
    assertSame(set, set.headSet("c"));
  }

  public void testEmpty_tailSet() {
    SortedSet<String> set = of();
    assertSame(set, set.tailSet("f"));
  }

  public void testEmpty_subSet() {

                flag.set(true)
                message.set("some value")
                number.set(1.23)
                list.set(listOf(1, 2))
                set.set(listOf(1, 2))
                map.set(mapOf(1 to true, 2 to false))
            }
        """

        when:
        run("someTask")

        then:
        outputContains("flag = true")

   *     operation
   */
  void clear();

  /**
   * Adds all of the ranges from the specified range set to this range set (optional operation).
   * After this operation, this range set is the minimal range set that {@linkplain
   * #enclosesAll(RangeSet) encloses} both the original range set and {@code other}.
   *
   * <p>This is equivalent to calling {@link #add} on each of the ranges in {@code other} in turn.
   *

   *     operation
   */
  void clear();

  /**
   * Adds all of the ranges from the specified range set to this range set (optional operation).
   * After this operation, this range set is the minimal range set that {@linkplain
   * #enclosesAll(RangeSet) encloses} both the original range set and {@code other}.
   *
   * <p>This is equivalent to calling {@link #add} on each of the ranges in {@code other} in turn.
   *

        property.set(someValue())
        property.set((String) null)

        expect:
        !property.present
        property.getOrNull() == null
        property.getOrElse(someValue()) == someValue()
        property.getOrElse(null) == null
    }

    def "can't set null provider to discard value"() {
        given:
        def property = property()
        property.set(someValue())

      }
    }
    return features;
  }

  /**
   * Given a set of features, return a new set of all features directly or indirectly implied by any
   * of them.
   *
   * @param features the set of features whose implications to find
   * @return the implied set of features
   */
  public static Set<Feature<?>> impliedFeatures(Set<Feature<?>> features) {
    Set<Feature<?>> impliedSet = new LinkedHashSet<>();

    #set ( $types = { } )
    #set ( $imports = $class.getClass().forName("java.util.TreeSet").newInstance() )
    #set ( $dummy = $imports.add( "java.io.Serializable" ) )
    #set ( $dummy = $imports.add( "java.util.AbstractList" ) )
    #set ( $dummy = $imports.add( "java.util.Collections" ) )
    #set ( $dummy = $imports.add( "java.util.HashMap" ) )
    #set ( $dummy = $imports.add( "java.util.List" ) )

    ImmutableSortedSet<Integer> set = ContiguousSet.create(Range.closed(1, 3), integers());
    assertFalse(set.contains(0));
    assertTrue(set.contains(1));
    assertTrue(set.contains(2));
    assertTrue(set.contains(3));
    assertFalse(set.contains(4));
    set = ContiguousSet.create(Range.open(0, 4), integers());
    assertFalse(set.contains(0));
    assertTrue(set.contains(1));
    assertTrue(set.contains(2));

    #set ( $types = { } )
    #set ( $imports = $class.getClass().forName("java.util.TreeSet").newInstance() )
    #set ( $dummy = $imports.add( "java.io.Serializable" ) )
    #set ( $dummy = $imports.add( "java.util.Collections" ) )
    #set ( $dummy = $imports.add( "java.util.HashMap" ) )
    #set ( $dummy = $imports.add( "java.util.Map" ) )