@GwtCompatible
@ElementTypesAreNonnullByDefault
/*
 * The type parameter is <T> rather than <T extends @Nullable> so that we can use T in the
 * doEquivalent and doHash methods to indicate that the parameter cannot be null.
 */
public abstract class Equivalence<T> implements BiPredicate<@Nullable T, @Nullable T> {
  /** Constructor for use by subclasses. */
  protected Equivalence() {}

  /**

/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

 * effect on the receiving instance; you must store and use the new splitter instance it returns
 * instead.
 *
 * <pre>{@code
 * // Do NOT do this
 * Splitter splitter = Splitter.on('/');
 * splitter.trimResults(); // does nothing!
 * return splitter.split("wrong / wrong / wrong");
 * }</pre>
 *
 * <p>For separator-based splitters that do not use {@code omitEmptyStrings}, an input string

    throw new InvalidObjectException("Use SerializedForm");
  }

  /**
   * Not supported. Use {@link #toImmutableSortedMultiset} instead. This method exists only to hide
   * {@link ImmutableMultiset#toImmutableMultiset} from consumers of {@code
   * ImmutableSortedMultiset}.
   *
   * @throws UnsupportedOperationException always
   * @deprecated Use {@link ImmutableSortedMultiset#toImmutableSortedMultiset}.

     *     <li> retrieve the 'combine.children' attribute on the dominant node, and try to match against
     *          'append'...</li>
     *     <li> if it matches 'append', then set mergeChildren == false...the recessive children will be appended as
     *          siblings of the dominant children.</li>

  /**
   * Returns the contained instance if it is present; {@code defaultValue} otherwise. If no default
   * value should be required because the instance is known to be present, use {@link #get()}
   * instead. For a default value of {@code null}, use {@link #orNull}.
   *
   * <p>Note about generics: The signature {@code public T or(T defaultValue)} is overly

/*
 * Copyright (C) 2009 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License

/*
 * Copyright (C) 2007 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

   * can use {@link com.google.common.collect.Maps#asConverter Maps.asConverter} instead to get a
   * function that also supports reverse conversion.
   *
   * <p><b>Java 8+ users:</b> if you are okay with {@code null} being returned for an unrecognized
   * key (instead of an exception being thrown), you can use the method reference {@code map::get}
   * instead.
   */

   *
   * <p><b>Note:</b> essentially the only reason to use this method is when you will need to add or
   * remove elements later. Otherwise, for non-null elements use {@link ImmutableList#of()} (for
   * varargs) or {@link ImmutableList#copyOf(Object[])} (for an array) instead. If any elements
   * might be null, or you need support for {@link List#set(int, Object)}, use {@link
   * Arrays#asList}.
   *