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)

    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)

    private @Nullable Iterator<? extends Iterator<? extends T>> getTopMetaIterator() {
      while (topMetaIterator == null || !topMetaIterator.hasNext()) {
        if (metaIterators != null && !metaIterators.isEmpty()) {
          topMetaIterator = metaIterators.removeFirst();
        } else {
          return null;
        }
      }
      return topMetaIterator;

//
// 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

        if (opLambda != null) {
            opLambda.callback(builder);
        }
    }

    public void setId_NotEqual(String id) {
        setId_NotTerm(id, null);
    }

    public void setId_NotTerm(String id) {
        setId_NotTerm(id, null);
    }

    public void setId_NotEqual(String id, ConditionOptionCall<BoolQueryBuilder> opLambda) {

        DataConfigCQ cq = new DataConfigCQ();
        if (queryLambda != null) {
            queryLambda.callback(cq);
        }
        FilterAggregationBuilder builder = regFilterA(name, cq.getQuery());
        if (opLambda != null) {
            opLambda.callback(builder);
        }
        if (aggsLambda != null) {
            DataConfigCA ca = new DataConfigCA();
            aggsLambda.callback(ca);

        if (opLambda != null) {
            opLambda.callback(builder);
        }
    }

    public void setId_NotEqual(String id) {
        setId_NotTerm(id, null);
    }

    public void setId_NotTerm(String id) {
        setId_NotTerm(id, null);
    }

    public void setId_NotEqual(String id, ConditionOptionCall<BoolQueryBuilder> opLambda) {

        if (opLambda != null) {
            opLambda.callback(builder);
        }
    }

    public void setId_NotEqual(String id) {
        setId_NotTerm(id, null);
    }

    public void setId_NotTerm(String id) {
        setId_NotTerm(id, null);
    }

    public void setId_NotEqual(String id, ConditionOptionCall<BoolQueryBuilder> opLambda) {

        if (opLambda != null) {
            opLambda.callback(builder);
        }
    }

    public void setId_NotEqual(String id) {
        setId_NotTerm(id, null);
    }

    public void setId_NotTerm(String id) {
        setId_NotTerm(id, null);
    }

    public void setId_NotEqual(String id, ConditionOptionCall<BoolQueryBuilder> opLambda) {

        if (opLambda != null) {
            opLambda.callback(builder);
        }
    }

    public void setId_NotEqual(String id) {
        setId_NotTerm(id, null);
    }

    public void setId_NotTerm(String id) {
        setId_NotTerm(id, null);
    }

    public void setId_NotEqual(String id, ConditionOptionCall<BoolQueryBuilder> opLambda) {