//
// Any NULL and non-NULL value combinations for (`run_options`,
// `run_metadata`) are valid.
//
//    - `run_options` may be NULL, in which case it will be ignored; or
//      non-NULL, in which case it must point to a `TF_Buffer` containing the
//      serialized representation of a `RunOptions` protocol buffer.
//    - `run_metadata` may be NULL, in which case it will be ignored; or

      synchronized (mutex) {
        Collection<V> collection = super.get(key);
        return (collection == null) ? null : typePreservingCollection(collection, mutex);
      }
    }

    @Override
    public Set<Map.Entry<K, Collection<V>>> entrySet() {
      synchronized (mutex) {
        if (asMapEntrySet == null) {
          asMapEntrySet = new SynchronizedAsMapEntries<>(delegate().entrySet(), mutex);
        }

      synchronized (mutex) {
        Collection<V> collection = super.get(key);
        return (collection == null) ? null : typePreservingCollection(collection, mutex);
      }
    }

    @Override
    public Set<Map.Entry<K, Collection<V>>> entrySet() {
      synchronized (mutex) {
        if (asMapEntrySet == null) {
          asMapEntrySet = new SynchronizedAsMapEntries<>(delegate().entrySet(), mutex);
        }

   * removal operations, and these are reflected in the underlying map.
   *
   * <p>It's acceptable for the underlying map to contain null keys, and even null values provided
   * that the function is capable of accepting null input. The transformed map might contain null
   * values, if the function sometimes gives a null result.
   *
   * <p>The returned map is not thread-safe or serializable, even if the underlying map is.
   *

   * removal operations, and these are reflected in the underlying map.
   *
   * <p>It's acceptable for the underlying map to contain null keys, and even null values provided
   * that the function is capable of accepting null input. The transformed map might contain null
   * values, if the function sometimes gives a null result.
   *
   * <p>The returned map is not thread-safe or serializable, even if the underlying map is.
   *

    protected final ColumnInfo _columnDepth = cci("depth", "depth", null, null, Integer.class, "depth", null, false, false, false,
            "Integer", 0, 0, null, null, false, null, null, null, null, null, false);
    protected final ColumnInfo _columnDescription = cci("description", "description", null, null, String.class, "description", null, false,

    protected final ColumnInfo _columnUpdatedTime = cci("updatedTime", "updatedTime", null, null, Long.class, "updatedTime", null, false,
            false, false, "Long", 0, 0, null, null, false, null, null, null, null, null, false);
    protected final ColumnInfo _columnUrls = cci("urls", "urls", null, null, String.class, "urls", null, false, false, false, "keyword", 0,

    List<@Nullable String> list = newArrayList("a", null, "b", null, "a", null);
    assertEquals(2, frequency(list.iterator(), "a"));
    assertEquals(1, frequency(list.iterator(), "b"));
    assertEquals(0, frequency(list.iterator(), "c"));
    assertEquals(0, frequency(list.iterator(), 4.2));
    assertEquals(3, frequency(list.iterator(), null));
  }

  @GwtIncompatible // slow (~4s)

    protected final ColumnInfo _columnPassword = cci("password", "password", null, null, String.class, "password", null, false, false,
            false, "keyword", 0, 0, null, null, false, null, null, null, null, null, false);
    protected final ColumnInfo _columnPort = cci("port", "port", null, null, Integer.class, "port", null, false, false, false, "Integer", 0,

    protected final ColumnInfo _columnValue = cci("value", "value", null, null, String.class, "value", null, false, false, false, "keyword",
            0, 0, null, null, false, null, null, null, null, null, false);
    protected final ColumnInfo _columnVirtualHost = cci("virtualHost", "virtualHost", null, null, String.class, "virtualHost", null, false,