* the behavior of this method is undefined but we make a reasonable effort at converting anyway.
   */
  public final String to(CaseFormat format, String str) {
    checkNotNull(format);
    checkNotNull(str);
    return (format == this) ? str : convert(format, str);
  }

  /** Enum values can override for performance reasons. */
  String convert(CaseFormat format, String s) {

    return null;
  }

  @CanIgnoreReturnValue
  @Override
  public @Nullable V put(K key, V value) {
    synchronized (lock) {
      checkNotNull(key);
      checkNotNull(value);
      Timestamped<V> oldValue = cachingHashMap.put(key, new Timestamped<V>(value, ticker));
      if (oldValue == null) {
        return null;
      }

    }

    final void addDelayedShutdownHook(
        ExecutorService service, long terminationTimeout, TimeUnit timeUnit) {
      checkNotNull(service);
      checkNotNull(timeUnit);
      addShutdownHook(
          newThread(
              "DelayedShutdownHook-for-" + service,
              () -> {
                service.shutdown();
                try {

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.collect.CollectPreconditions.checkNonnegative;

import com.google.common.annotations.GwtCompatible;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;

    checkNotClosed();
    target.append((char) c);
  }

  @Override
  public void write(String str) throws IOException {
    checkNotNull(str);
    checkNotClosed();
    target.append(str);
  }

  @Override
  public void write(String str, int off, int len) throws IOException {
    checkNotNull(str);
    checkNotClosed();
    // tricky: append takes start, end pair...
    target.append(str, off, off + len);
  }

    private final Function<B, C> g;
    private final Function<A, ? extends B> f;

    FunctionComposition(Function<B, C> g, Function<A, ? extends B> f) {
      this.g = checkNotNull(g);
      this.f = checkNotNull(f);
    }

    @Override
    @ParametricNullness
    public C apply(@ParametricNullness A a) {
      return g.apply(f.apply(a));
    }

    @Override

    final List<F> fromList;
    final Function<? super F, ? extends T> function;

    TransformingSequentialList(List<F> fromList, Function<? super F, ? extends T> function) {
      this.fromList = checkNotNull(fromList);
      this.function = checkNotNull(function);
    }

    /**
     * The default implementation inherited is based on iteration and removal of each element which

  static <K, V> CacheLoader<K, V> errorLoader(Error e) {
    checkNotNull(e);
    return new CacheLoader<K, V>() {
      @Override
      public V load(K key) {
        throw e;
      }
    };
  }

  /** Returns a {@link CacheLoader} that throws the given exception for every request. */
  static <K, V> CacheLoader<K, V> exceptionLoader(Exception e) {
    checkNotNull(e);
    return new CacheLoader<K, V>() {
      @Override

   * the behavior of this method is undefined but we make a reasonable effort at converting anyway.
   */
  public final String to(CaseFormat format, String str) {
    checkNotNull(format);
    checkNotNull(str);
    return (format == this) ? str : convert(format, str);
  }

  /** Enum values can override for performance reasons. */
  String convert(CaseFormat format, String s) {

    }

    return new FilteredCollection<>(checkNotNull(unfiltered), checkNotNull(predicate));
  }

  /**
   * Delegates to {@link Collection#contains}. Returns {@code false} if the {@code contains} method
   * throws a {@code ClassCastException} or {@code NullPointerException}.
   */
  static boolean safeContains(Collection<?> collection, @Nullable Object object) {
    checkNotNull(collection);
    try {