static <E> Collector<E, ?, ImmutableList<E>> toImmutableList() {
    return (Collector) TO_IMMUTABLE_LIST;
  }

  // Sets

  @SuppressWarnings({"rawtypes", "unchecked"})
  static <E> Collector<E, ?, ImmutableSet<E>> toImmutableSet() {
    return (Collector) TO_IMMUTABLE_SET;
  }

  static <E> Collector<E, ?, ImmutableSortedSet<E>> toImmutableSortedSet(
      Comparator<? super E> comparator) {

  @SuppressWarnings({"rawtypes", "unchecked"})
  static <E> Collector<E, ?, ImmutableList<E>> toImmutableList() {
    return (Collector) TO_IMMUTABLE_LIST;
  }

  // Sets

  @SuppressWarnings({"rawtypes", "unchecked"})
  static <E> Collector<E, ?, ImmutableSet<E>> toImmutableSet() {
    return (Collector) TO_IMMUTABLE_SET;
  }

  static <E> Collector<E, ?, ImmutableSortedSet<E>> toImmutableSortedSet(

		}
	}

	// Prepare to register the collectors. Other than `MetricGroup` collectors,
	// we also have standard collectors like `GoCollector`.

	// Create all Non-`MetricGroup` collectors here.
	collectors := map[collectorPath]prometheus.Collector{
		systemGoCollectorPath: collectors.NewGoCollector(),
	}

	// Add all `MetricGroup` collectors to the map.
	for _, mg := range allMetricGroups {

    Collector<Cell<String, String, Integer>, ?, ImmutableTable<String, String, Integer>> collector =
        TableCollectors.toImmutableTable(Cell::getRowKey, Cell::getColumnKey, t -> null);
    try {
      Stream.of(immutableCell("one", "uno", 1)).collect(collector);
      fail("Expected NullPointerException");
    } catch (NullPointerException expected) {
    }
    collector =

            jumpExpressions = jumpExpressions,
            hasJumps = collector.hasJumps,
            hasEscapingJumps = graphIndex.computeHasEscapingJumps(firDefaultStatement, collector),
            hasMultipleJumpKinds = collector.hasMultipleJumpKinds,
            hasMultipleJumpTargets = graphIndex.computeHasMultipleJumpTargets(collector),
            variableReassignments = collector.variableReassignments
        )
    }

    checkNonnegative(k, "k");
    checkNotNull(comparator);
    return Collector.of(
        () -> TopKSelector.<T>least(k, comparator),
        TopKSelector::offer,
        TopKSelector::combine,
        TopKSelector::topK,
        Collector.Characteristics.UNORDERED);
  }

  /**
   * Returns a {@code Collector} that returns the {@code k} greatest (relative to the specified

    assertNotSame(sortedSet, copy);
  }

  public void testToImmutableSet() {
    Collector<String, ?, ImmutableSet<String>> collector = ImmutableSet.toImmutableSet();
    Equivalence<ImmutableSet<String>> equivalence =
        Equivalence.equals().onResultOf(ImmutableSet::asList);
    CollectorTester.of(collector, equivalence)
        .expectCollects(ImmutableSet.of("a", "b", "c", "d"), "a", "b", "a", "c", "b", "b", "d");
  }

        private final OutputStream collector;


        public CacheStream ( OutputStream stream, OutputStream collector ) {
            this.stream = stream;
            this.collector = collector;
        }


        @Override
        public void close () throws IOException {
            this.stream.close();
            this.collector.close();
        }


        @Override

  public static <T extends @Nullable Object> Collector<T, ?, List<T>> least(
      int k, Comparator<? super T> comparator) {
    checkNonnegative(k, "k");
    checkNotNull(comparator);
    return Collector.of(
        () -> TopKSelector.<T>least(k, comparator),
        TopKSelector::offer,
        TopKSelector::combine,
        TopKSelector::topK,
        Collector.Characteristics.UNORDERED);
  }

  /**

        private final OutputStream stream;

        private final OutputStream collector;

        public CacheStream(OutputStream stream, OutputStream collector) {
            this.stream = stream;
            this.collector = collector;
        }

        public void close() throws IOException {
            stream.close();
            collector.close();
        }

        public void flush() throws IOException {