* limitations under the License.
 */

package com.google.common.collect.testing.testers;

import static com.google.common.collect.testing.features.CollectionFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION;
import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_ITERATOR_REMOVE;
import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_REMOVE;

import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_VALUES;
import static com.google.common.collect.testing.features.MapFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION;
import static com.google.common.collect.testing.features.MapFeature.SUPPORTS_PUT;
import static java.util.Collections.singletonList;

import com.google.common.annotations.GwtCompatible;

import static com.google.common.collect.testing.features.CollectionFeature.ALLOWS_NULL_VALUES;
import static com.google.common.collect.testing.features.CollectionFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION;
import static com.google.common.collect.testing.features.CollectionFeature.RESTRICTS_ELEMENTS;
import static com.google.common.collect.testing.features.CollectionFeature.SUPPORTS_ADD;

    List<Feature<?>> allFeatures =
        Arrays.<Feature<?>>asList(
            CollectionSize.ANY,
            CollectionFeature.ALLOWS_NULL_VALUES,
            CollectionFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION,
            CollectionFeature.GENERAL_PURPOSE,
            CollectionFeature.REMOVE_OPERATIONS,
            CollectionFeature.SERIALIZABLE,
            CollectionFeature.SUPPORTS_ADD,

  /**
   * Returns a copy of the input string in which all {@linkplain #isUpperCase(char) uppercase ASCII
   * characters} have been converted to lowercase. All other characters are copied without
   * modification.
   */
  public static String toLowerCase(String string) {
    int length = string.length();
    for (int i = 0; i < length; i++) {
      if (isUpperCase(string.charAt(i))) {

    List<Feature<?>> allFeatures =
        Arrays.<Feature<?>>asList(
            CollectionSize.ANY,
            CollectionFeature.ALLOWS_NULL_VALUES,
            CollectionFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION,
            CollectionFeature.GENERAL_PURPOSE,
            CollectionFeature.REMOVE_OPERATIONS,
            CollectionFeature.SERIALIZABLE,
            CollectionFeature.SUPPORTS_ADD,

    suite.addTest(
        MultisetTestSuiteBuilder.using(hashMultisetGenerator())
            .withFeatures(
                CollectionSize.ANY,
                CollectionFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION,
                CollectionFeature.ALLOWS_NULL_VALUES,
                CollectionFeature.SERIALIZABLE,
                CollectionFeature.GENERAL_PURPOSE,
                MultisetFeature.ENTRIES_ARE_VIEWS)

 * }</pre>
 *
 * <h3>Views</h3>
 *
 * <p>Much of the power of the multimap API comes from the <i>view collections</i> it provides.
 * These always reflect the latest state of the multimap itself. When they support modification, the
 * changes are <i>write-through</i> (they automatically update the backing multimap). These view
 * collections are:
 *
 * <ul>
 *   <li>{@link #asMap}, mentioned above

      /*
       * requireNonNull is safe as long as callers pass a nextSibling that (a) has the same key and
       * (b) is present in the multimap. (And they do, except maybe in case of concurrent
       * modification, in which case all bets are off.)
       */
      KeyList<K, V> keyList = requireNonNull(keyToKeyList.get(key));
      keyList.count++;
      node.previous = nextSibling.previous;

    cycle.remove();
    assertEquals(Collections.emptyList(), iterable);
    assertFalse(cycle.hasNext());
  }

  /** An Iterable whose Iterator is rigorous in checking for concurrent modification. */
  private static final class PickyIterable<E> implements Iterable<E> {
    final List<E> elements;
    int modCount = 0;

    PickyIterable(E... elements) {