* if occurrences == 0. This satisfies both NullPointerTester and
   * CollectionRemoveTester.testRemove_nullAllowed, but it's not clear that it's
   * a good policy, especially because, in order for the test to pass, the
   * parameter must be misleadingly annotated as @Nullable. I suspect that
   * we'll want to remove @Nullable, add an eager checkNotNull, and loosen up

   */
  @Override
  public ImmutableSet<K> keySet() {
    ImmutableSet<K> result = keySet;
    return (result == null) ? keySet = createKeySet() : result;
  }

  /*
   * This could have a good default implementation of return new ImmutableKeySet<K, V>(this),
   * but ProGuard can't figure out how to eliminate that default when RegularImmutableMap
   * overrides it.
   */

                <!-- TODO(cpovirk): Enable NullArgumentForNonNullParameter for
                     prod code. It's disabled automatically for "test code"
                     (which is good: our tests have intentional violations), but
                     Error Prone doesn't know it's building test code unless we
                     pass -XepCompilingTestOnlyCode, and that argument needs to

  }

  /**
   * All of the infrastructure of split and splitToString is identical, so we do one test of
   * splitToString. All other cases should be covered by testing of split.
   *
   * <p>TODO(user): It would be good to make all the relevant tests run on both split and
   * splitToString automatically.
   */
  public void testCharacterSimpleSplitToList() {
    String simple = "a,b,c";

   */
  public static double constrainToRange(double value, double min, double max) {
    // avoid auto-boxing by not using Preconditions.checkArgument(); see Guava issue 3984
    // Reject NaN by testing for the good case (min <= max) instead of the bad (min > max).
    if (min <= max) {
      return Math.min(Math.max(value, min), max);
    }
    throw new IllegalArgumentException(

    // do n swaps, minus a delta (0 or 2 for Reversal, gcd(d, n) for Successive), so that's about
    // twice as many reads and writes. But benchmarking shows that they usually perform better than
    // Dolphin. Reversal is about as good as Successive on average, and it is much simpler,
    // especially since we already have a `reverse` method.
    checkNotNull(array);
    checkPositionIndexes(fromIndex, toIndex, array.length);
    if (array.length <= 1) {

    // whose key property is that it maps 25 characters into the 32-slot table without collision.
    // Basically this is an opportunistic fast implementation as opposed to "good code". For most
    // other use-cases, the reduction in readability isn't worth it.
    static final String TABLE =
        "\u2002\u3000\r\u0085\u200A\u2005\u2000\u3000"

  private Element[] createQueries(Set<Element> elementsInSet, int numQueries) {
    List<Element> queryList = Lists.newArrayListWithCapacity(numQueries);

    int numGoodQueries = (int) (numQueries * hitRate + 0.5);

    // add good queries
    int size = elementsInSet.size();
    if (size > 0) {
      int minCopiesOfEachGoodQuery = numGoodQueries / size;
      int extras = numGoodQueries % size;

import java.util.Collections;
import java.util.Iterator;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A utility for testing an Iterator implementation by comparing its behavior to that of a "known
 * good" reference implementation. In order to accomplish this, it's important to test a great
 * variety of sequences of the {@link Iterator#next}, {@link Iterator#hasNext} and {@link

    }

    /**
     * Careful here: if threads are mutating the atomicLongArray while this method is executing, the
     * final long[] will be a "rolling snapshot" of the state of the bit array. This is usually good
     * enough, but should be kept in mind.
     */
    public static long[] toPlainArray(AtomicLongArray atomicLongArray) {
      long[] array = new long[atomicLongArray.length()];