/**
   * 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)

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 com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;

 * }</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

import static com.google.common.collect.testing.features.CollectionSize.ZERO;
import static com.google.common.collect.testing.features.MapFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION;
import static com.google.common.collect.testing.features.MapFeature.SUPPORTS_REMOVE;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.AbstractMapTester;

 * 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_REMOVE;
import static com.google.common.collect.testing.features.CollectionSize.SEVERAL;

        .withFeatures(
            SetFeature.GENERAL_PURPOSE,
            CollectionFeature.KNOWN_ORDER,
            CollectionFeature.SERIALIZABLE,
            CollectionFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION,
            CollectionFeature.RESTRICTS_ELEMENTS,
            CollectionSize.ANY)
        .suppressing(suppressForCheckedNavigableSet())
        .createTestSuite();
  }

  public Test testsForEmptySet() {

   * implementation-dependent). Furthermore, implementations are not required to support
   * modifications to the entry set at all, and the {@code Entry} instances themselves don't even
   * have methods for modification. See the specific implementation class for more details on how
   * its entry set handles modifications.
   *
   * @return a set of entries representing the data of this multiset
   */
  Set<Entry<E>> entrySet();

import static com.google.common.collect.testing.features.MapFeature.ALLOWS_NULL_KEY_QUERIES;
import static com.google.common.collect.testing.features.MapFeature.FAILS_FAST_ON_CONCURRENT_MODIFICATION;
import static com.google.common.collect.testing.features.MapFeature.SUPPORTS_REMOVE;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.testing.AbstractMapTester;