A accum = collector.supplier().get();
        for (T input : inputs) {
          A newAccum = collector.supplier().get();
          collector.accumulator().accept(newAccum, input);
          accum = collector.combiner().apply(accum, newAccum);
        }
        return accum;
      }
    },
    /** Get one accumulator for each element and merge the accumulators right-to-left. */
    MERGE_RIGHT_ASSOCIATIVE {
      @Override

        A accum = collector.supplier().get();
        for (T input : inputs) {
          A newAccum = collector.supplier().get();
          collector.accumulator().accept(newAccum, input);
          accum = collector.combiner().apply(accum, newAccum);
        }
        return accum;
      }
    },
    /** Get one accumulator for each element and merge the accumulators right-to-left. */
    MERGE_RIGHT_ASSOCIATIVE {
      @Override

     * Anyway, the purpose of this method is to implement a BinaryOperator combiner for a Collector,
     * so its return value will get used naturally.
     */
    @SuppressWarnings("CanIgnoreReturnValueSuggester")
    ImmutableTableCollectorState<R, C, V> combine(
        ImmutableTableCollectorState<R, C, V> other, BinaryOperator<V> merger) {

     * Anyway, the purpose of this method is to implement a BinaryOperator combiner for a Collector,
     * so its return value will get used naturally.
     */
    @SuppressWarnings("CanIgnoreReturnValueSuggester")
    ImmutableTableCollectorState<R, C, V> combine(
        ImmutableTableCollectorState<R, C, V> other, BinaryOperator<V> merger) {

    @RetainedLocalRef List<@Nullable Present<V>> localValues = values;
    if (localValues != null) {
      set(combine(localValues));
    }
  }

  @Override
  void releaseResources(ReleaseResourcesReason reason) {
    super.releaseResources(reason);
    this.values = null;
  }

  abstract C combine(List<@Nullable Present<V>> values);

  /** Used for {@link Futures#allAsList} and {@link Futures#successfulAsList}. */

   */
  private static final Collector<Object, ?, Optional<Object>> TO_OPTIONAL =
      Collector.of(
          ToOptionalState::new,
          ToOptionalState::add,
          ToOptionalState::combine,
          ToOptionalState::getOptional,
          Collector.Characteristics.UNORDERED);

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

      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <executions>
          <execution>
            <id>default-compile</id>
            <configuration>
              <compilerArgs combine.children="append" combine.self="append">
                <arg>-XDignore.symbol.file</arg>
              </compilerArgs>
            </configuration>
          </execution>
          <execution>
            <id>compile-java9</id>

      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <executions>
          <execution>
            <id>default-compile</id>
            <configuration>
              <compilerArgs combine.children="append" combine.self="append">
                <arg>-XDignore.symbol.file</arg>
              </compilerArgs>
            </configuration>
          </execution>
          <execution>
            <id>compile-java9</id>

        <artifactId>maven-compiler-plugin</artifactId>
        <executions>
          <execution>
            <id>default-compile</id>
            <configuration>
              <compilerArgs combine.children="append" combine.self="append">
                <arg>-XDignore.symbol.file</arg>
              </compilerArgs>
            </configuration>
          </execution>
          <execution>
            <id>compile-java9</id>

   */
  private static final Collector<Object, ?, Optional<Object>> TO_OPTIONAL =
      Collector.of(
          ToOptionalState::new,
          ToOptionalState::add,
          ToOptionalState::combine,
          ToOptionalState::getOptional,
          Collector.Characteristics.UNORDERED);

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