* <i>if and only if</i> {@code a.equals(b)}. If this advice is not followed, the resulting map will
 * not correctly obey its specification.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
 *
 * @author Jared Levy
 * @author Louis Wasserman
 * @since 2.0 (implements {@code NavigableMap} since 12.0)
 */

import java.util.Collection;
import java.util.Map;
import java.util.Set;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Implementation of {@link Multimap} using hash tables.
 *
 * <p>The multimap does not store duplicate key-value pairs. Adding a new key-value pair equal to an
 * existing key-value pair has no effect.
 *

   * be declared as a {@code List}.
   *
   * <p>Note also that serialization is not in general required to return an object that is
   * {@linkplain Object#equals equal} to the original, nor is it required to return even an object
   * of the same class. For example, if sublists of {@code MyList} instances were serializable,

    File i18nFile = getTestFile("i18n.txt");
    assertFalse(Files.equal(asciiFile, i18nFile));
    assertTrue(Files.equal(asciiFile, asciiFile));

    File temp = createTempFile();
    Files.copy(asciiFile, temp);
    assertTrue(Files.equal(asciiFile, temp));

    Files.copy(i18nFile, temp);
    assertTrue(Files.equal(i18nFile, temp));

    Files.copy(asciiFile, temp);

            // 2.0.X == 2-X == 2.0.0.X for any string x
            checkVersionsEqual("2-" + x, "2.0." + x); // previously ordered, now equals
            checkVersionsEqual("2-" + x, "2.0.0." + x); // previously ordered, now equals
            checkVersionsEqual("2.0." + x, "2.0.0." + x); // previously ordered, now equals
        }
    }

    @Test
    public void testMng7714() {

   * predicate)} and use the copy.
   *
   * <p><b>Warning:</b> {@code predicate} must be <i>consistent with equals</i>, as documented at
   * {@link Predicate#apply}. Do not provide a predicate such as {@code
   * Predicates.instanceOf(ArrayList.class)}, which is inconsistent with equals. (See {@link
   * Iterables#filter(Iterable, Class)} for related functionality.)
   *

  }

  @Override
  public int hashCode() { // delegate to 's'
    return s.hashCode();
  }

  @Override
  public boolean equals(@Nullable Object other) {
    if (other == null) {
      return false;
    } else if (other instanceof BaseComparable) {
      return s.equals(((BaseComparable) other).s);
    } else {
      return false;
    }
  }

  @Override
  public int compareTo(BaseComparable o) {

import java.util.TreeSet;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicInteger;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.NonNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A comparator, with additional methods to support common operations. This is an "enriched" version

    return comparator.compare(a, b);
  }

  @Override
  public boolean equals(@CheckForNull Object object) {
    if (object == this) {
      return true;
    }
    if (object instanceof ComparatorOrdering) {
      ComparatorOrdering<?> that = (ComparatorOrdering<?>) object;
      return this.comparator.equals(that.comparator);
    }
    return false;
  }

  @Override
  public int hashCode() {

     * represent the same element and count. That is, two entries {@code a} and {@code b} are equal
     * if:
     *
     * <pre>{@code
     * Objects.equal(a.getElement(), b.getElement())
     *     && a.getCount() == b.getCount()
     * }</pre>
     */
    @Override
    // TODO(kevinb): check this wrt TreeMultiset?
    boolean equals(@CheckForNull Object o);

    /**
     * {@inheritDoc}
     *