}
	}

	// 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{
		debugGoCollectorPath: collectors.NewGoCollector(),
	}

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

}


private
class CompositeVersionsToIncubatingCollector(

    private
    val collectors: List<VersionsToIncubatingCollector>

) : VersionsToIncubatingCollector {

    override fun collectFrom(sourceFile: File): VersionsToIncubating =
        collectors
            .flatMap { it.collectFrom(sourceFile).entries }
            .associate { it.key to it.value }
}


private

/**
 * Collectors not present in {@code java.util.stream.Collectors} that are not otherwise associated
 * with a {@code com.google.common} type.
 *
 * @author Louis Wasserman
 * @since 21.0
 */
@GwtCompatible
public final class MoreCollectors {

  /*
   * TODO(lowasser): figure out if we can convert this to a concurrent AtomicReference-based
   * collector without breaking j2cl?
   */

import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collector;
import org.jspecify.annotations.Nullable;

/** Collectors utilities for {@code common.collect.Table} internals. */
@GwtCompatible
final class TableCollectors {

  static <T extends @Nullable Object, R, C, V>
      Collector<T, ?, ImmutableTable<R, C, V>> toImmutableTable(
          Function<? super T, ? extends R> rowFunction,

   * collector without breaking j2cl?
   */
  private static final Collector<Object, ?, Optional<Object>> TO_OPTIONAL =
      Collector.of(
          () -> new ToOptionalState<>(null),
          ToOptionalState::add,
          ToOptionalState::combine,
          ToOptionalState::getOptional,
          Collector.Characteristics.UNORDERED);

  /**
   * A collector that converts a stream of zero or one elements to an {@code Optional}.

  static <E> Collector<E, ?, ImmutableSet<E>> toImmutableSet() {
    return (Collector) TO_IMMUTABLE_SET;
  }

  static <E> Collector<E, ?, ImmutableSortedSet<E>> toImmutableSortedSet(
      Comparator<? super E> comparator) {
    checkNotNull(comparator);
    return Collector.of(
        () -> new ImmutableSortedSet.Builder<E>(comparator),
        ImmutableSortedSet.Builder::add,
        ImmutableSortedSet.Builder::combine,

import java.util.function.ToIntFunction;
import java.util.stream.Collector;
import java.util.stream.Stream;
import org.jspecify.annotations.Nullable;

/** Collectors utilities for {@code common.collect} internals. */
@GwtCompatible
final class CollectCollectors {

  private static final Collector<Object, ?, ImmutableList<Object>> TO_IMMUTABLE_LIST =
      Collector.of(
          ImmutableList::builder,

import java.util.function.Supplier;
import java.util.stream.Collector;
import org.jspecify.annotations.Nullable;

/** Collectors utilities for {@code common.collect.Table} internals. */
@GwtCompatible
@IgnoreJRERequirement // used only from APIs with Java 8 types in them
final class TableCollectors {

  static <T extends @Nullable Object, R, C, V>
      Collector<T, ?, ImmutableTable<R, C, V>> toImmutableTable(

   * operation is performed. (This differs from the {@code Collector} returned by {@link
   * Collectors#toMap(Function, Function)}, which throws an {@code IllegalStateException}.)
   *
   * @since 33.2.0 (available since 21.0 in guava-jre)
   */
  @IgnoreJRERequirement // Users will use this only if they're already using streams.
  public static <T extends @Nullable Object, K, V>
      Collector<T, ?, ImmutableBiMap<K, V>> toImmutableBiMap(

   * the collection operation is performed. (This differs from the {@code Collector} returned by
   * {@link Collectors#toMap(Function, Function)}, which throws an {@code IllegalStateException}.)
   *
   * @since NEXT
   */
  public static <T extends @Nullable Object, K extends Comparable<? super K>, V>
      Collector<T, ?, ImmutableSortedMap<K, V>> toImmutableSortedMap(
          Function<? super T, ? extends K> keyFunction,