return Collector.of(
        ImmutableTableCollectorState<R, C, V>::new,
        (state, input) ->
            state.put(
                rowFunction.apply(input),
                columnFunction.apply(input),
                valueFunction.apply(input),
                mergeFunction),
        (s1, s2) -> s1.combine(s2, mergeFunction),
        state -> state.toTable());
  }

  static <
          T extends @Nullable Object,

    // Fail fast on a null. We throw NPE here because the contract of Executor states that it throws
    // NPE on null listener, so we propagate that contract up into the add method as well.
    checkNotNull(runnable, "Runnable was null.");
    checkNotNull(executor, "Executor was null.");

    // Lock while we check state. We must maintain the lock while adding the new pair so that

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.annotation.CheckForNull;

/**
 * An {@link OutputStream} that starts buffering to a byte array, but switches to file buffering
 * once the data reaches a configurable size.
 *
 * <p>When this stream creates a temporary file, it restricts the file's permissions to the current

 *
 * <p>To use this class the concrete subclass must implement the {@link
 * IteratorTester#newTargetIterator()} method. This is because it's impossible to test an Iterator
 * without changing its state, so the tester needs a steady supply of fresh Iterators.
 *
 * <p>If your iterator supports modification through {@code remove()}, you may wish to override the

# Guava: Google Core Libraries for Java

[![Latest release](https://img.shields.io/github/release/google/guava.svg)](https://github.com/google/guava/releases/latest)
[![Build Status](https://github.com/google/guava/workflows/CI/badge.svg?branch=master)](https://github.com/google/guava/actions)
[![OpenSSF Best Practices](https://bestpractices.coreinfrastructure.org/projects/7197/badge)](https://bestpractices.coreinfrastructure.org/projects/7197)

      Collector.<@Nullable Object, ToOptionalState, @Nullable Object>of(
          ToOptionalState::new,
          (state, o) -> state.add((o == null) ? NULL_PLACEHOLDER : o),
          ToOptionalState::combine,
          state -> {
            Object result = state.getElement();
            return (result == NULL_PLACEHOLDER) ? null : result;
          },
          Collector.Characteristics.UNORDERED);

  /**

  interface ConcurrentlyMutatedList<E> extends List<E> {
    /**
     * The elements of a {@link ConcurrentlyMutatedList} are added and removed over time. This
     * method returns every state that the list has passed through at some point.
     */
    Set<List<E>> getAllStates();
  }

  /**
   * Returns a {@link ConcurrentlyMutatedList} that performs the given operations as its concurrent

 *
 * <p>To use this class the concrete subclass must implement the {@link
 * IteratorTester#newTargetIterator()} method. This is because it's impossible to test an Iterator
 * without changing its state, so the tester needs a steady supply of fresh Iterators.
 *
 * <p>If your iterator supports modification through {@code remove()}, you may wish to override the

  interface ConcurrentlyMutatedList<E> extends List<E> {
    /**
     * The elements of a {@link ConcurrentlyMutatedList} are added and removed over time. This
     * method returns every state that the list has passed through at some point.
     */
    Set<List<E>> getAllStates();
  }

  /**
   * Returns a {@link ConcurrentlyMutatedList} that performs the given operations as its concurrent