/**
     * Returns a new tree starting at this node, filtering the children.
     * Note that this node will not be filtered and only the children
     * and its descendant will be checked.
     *
     * @param filter the filter to apply
     * @return a new filtered graph
     */
    @Nonnull
    Node filter(@Nonnull Predicate<Node> filter);

    /**

# And golookup of a hash confirms that it still exists on the server.
# We can use that to revalidate that specific versions still exist and
# have the same meaning they did the last time we checked.
#
# Usage:
#
#	hg --config "extensions.goreposum=$GOROOT/lib/hg/goreposum.py" goreposum REPOURL

import base64, hashlib, sys
from mercurial import registrar, ui, hg, node
from mercurial.i18n import _

 *       String}.
 *   <li>{@code getElement} on a {@code Multiset.Entry<@Nullable String>} returns {@code @Nullable
 *       String}.
 * </ul>
 *
 * This is the same behavior as type-variable usages have to Kotlin and to the Checker Framework.
 * Contrast the method above to:
 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},

 *       String}.
 *   <li>{@code getElement} on a {@code Multiset.Entry<@Nullable String>} returns {@code @Nullable
 *       String}.
 * </ul>
 *
 * This is the same behavior as type-variable usages have to Kotlin and to the Checker Framework.
 * Contrast the method above to:
 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},

 *       String}.
 *   <li>{@code getElement} on a {@code Multiset.Entry<@Nullable String>} returns {@code @Nullable
 *       String}.
 * </ul>
 *
 * This is the same behavior as type-variable usages have to Kotlin and to the Checker Framework.
 * Contrast the method above to:
 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},

 *       String}.
 *   <li>{@code getElement} on a {@code Multiset.Entry<@Nullable String>} returns {@code @Nullable
 *       String}.
 * </ul>
 *
 * This is the same behavior as type-variable usages have to Kotlin and to the Checker Framework.
 * Contrast the method above to:
 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},

    clearCache();
    backingMap.clear();
  }

  @Nullable V get(Object key) {
    checkNotNull(key);
    V value = getIfCached(key);
    // TODO(b/192579700): Use a ternary once it no longer confuses our nullness checker.
    if (value == null) {
      return getWithoutCaching(key);
    } else {
      return value;
    }
  }

  final @Nullable V getWithoutCaching(Object key) {
    checkNotNull(key);

   *
   * <p>The returned array has all its elements set to their initial null values. However, we don't
   * declare it as {@code @Nullable ImmutableMapEntry[]} because our checker doesn't require newly
   * created arrays to have a {@code @Nullable} element type even when they're created directly with
   * {@code new ImmutableMapEntry[...]}, so it seems silly to insist on that only here.
   */

 *       String}.
 *   <li>{@code getElement} on a {@code Multiset.Entry<@Nullable String>} returns {@code @Nullable
 *       String}.
 * </ul>
 *
 * This is the same behavior as type-variable usages have to Kotlin and to the Checker Framework.
 * Contrast the method above to:
 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},

 *       String}.
 *   <li>{@code getElement} on a {@code Multiset.Entry<@Nullable String>} returns {@code @Nullable
 *       String}.
 * </ul>
 *
 * This is the same behavior as type-variable usages have to Kotlin and to the Checker Framework.
 * Contrast the method above to:
 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},