// ===================================================================================
    //                                                                           Singleton
    //                                                                           =========
    private static final SearchLogDbm _instance = new SearchLogDbm();

    private SearchLogDbm() {
    }

        rowFunction, columnFunction, valueFunction, mergeFunction);
  }

  /**
   * Returns an empty immutable table.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  @SuppressWarnings("unchecked")
  public static <R, C, V> ImmutableTable<R, C, V> of() {
    return (ImmutableTable<R, C, V>) SparseImmutableTable.EMPTY;
  }

    return CollectCollectors.toImmutableRangeMap(keyFunction, valueFunction);
  }

  /**
   * Returns an empty immutable range map.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  @SuppressWarnings("unchecked")
  public static <K extends Comparable<?>, V> ImmutableRangeMap<K, V> of() {
    return (ImmutableRangeMap<K, V>) EMPTY;
  }

   * {@code Optional.orElse(null)}.
   */
  @CheckForNull
  public abstract T orNull();

  /**
   * Returns an immutable singleton {@link Set} whose only element is the contained instance if it
   * is present; an empty immutable {@link Set} otherwise.
   *
   * <p><b>Comparison to {@code java.util.Optional}:</b> this method has no equivalent in Java 8's

    // ===================================================================================
    //                                                                           Singleton
    //                                                                           =========
    private static final WebConfigDbm _instance = new WebConfigDbm();

    private WebConfigDbm() {
    }

    return CollectCollectors.toImmutableRangeSet();
  }

  /**
   * Returns an empty immutable range set.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  @SuppressWarnings("unchecked")
  public static <C extends Comparable> ImmutableRangeSet<C> of() {
    return (ImmutableRangeSet<C>) EMPTY;
  }

  /**

 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.model.validation;

import javax.inject.Inject;
import javax.inject.Named;
import javax.inject.Singleton;

import java.io.File;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Deque;
import java.util.HashMap;
import java.util.HashSet;

    return CollectCollectors.toImmutableBiMap(keyFunction, valueFunction);
  }

  /**
   * Returns the empty bimap.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   */
  // Casting to any type is safe because the set will never hold any elements.
  @SuppressWarnings("unchecked")
  public static <K, V> ImmutableBiMap<K, V> of() {

    assertEvalsToFalse(nasty);

    Predicate<? super Integer> stillNasty = SerializableTester.reserializeAndAssert(nasty);

    assertEvalsToFalse(stillNasty);
  }

  // enum singleton pattern
  private enum TrimStringFunction implements Function<String, String> {
    INSTANCE;

    @Override
    public String apply(String string) {
      return whitespace().trimFrom(string);
    }
  }

 *
 * <p>Expressing the immutability guarantee directly in the type that user code references is a
 * powerful advantage. Although Java offers certain immutable collection factory methods, such as
 * {@link Collections#singleton(Object)} and <a
 * href="https://docs.oracle.com/javase/9/docs/api/java/util/Set.html#immutable">{@code Set.of}</a>,
 * we recommend using <i>these</i> classes instead for this reason (as well as for consistency).
 *