assertEquals(SsoResponseType.class, SsoResponseType.LOGOUT.getDeclaringClass());
    }

    @Test
    public void test_enumConstantReference() {
        // Test that enum constants are singleton instances
        SsoResponseType metadata1 = SsoResponseType.METADATA;
        SsoResponseType metadata2 = SsoResponseType.valueOf("METADATA");
        assertSame(metadata1, metadata2);

      new ImmutableClassToInstanceMap<>(ImmutableMap.of());

  /**
   * Returns an empty {@code ImmutableClassToInstanceMap}.
   *
   * <p><b>Performance note:</b> the instance returned is a singleton.
   *
   * @since 19.0
   */
  @SuppressWarnings("unchecked")
  public static <B> ImmutableClassToInstanceMap<B> of() {
    return (ImmutableClassToInstanceMap<B>) EMPTY;
  }

  /**

   * the JDK {@link java.util.function.Function} class, see {@link Function}.
   */
  public static Function<Object, String> toStringFunction() {
    return ToStringFunction.INSTANCE;
  }

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

    @Override
    public String apply(Object o) {
      checkNotNull(o); // eager for GWT.
      return o.toString();

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

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

import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.regex.Pattern;

import org.apache.maven.settings.Mirror;
import org.apache.maven.settings.Profile;

    }

    @Override
    public Map<String, Collection<Integer>> create(Object... elements) {
      ImmutableMap.Builder<String, Integer> builder = ImmutableMap.builder();
      // assumes that each set is a singleton or less (as is done for the samples)
      for (Object elem : elements) {
        @SuppressWarnings("unchecked") // safe by generator contract

import org.apache.maven.api.di.Inject;
import org.apache.maven.api.di.Named;
import org.apache.maven.api.di.Priority;
import org.apache.maven.api.di.Provides;
import org.apache.maven.api.di.Singleton;
import org.apache.maven.api.di.Typed;
import org.apache.maven.api.services.Lookup;
import org.apache.maven.api.services.ToolchainFactoryException;
import org.apache.maven.api.services.ToolchainManagerException;

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

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

import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;

import java.util.List;
import java.util.Map;
import java.util.Objects;

import org.apache.maven.api.di.Inject;
import org.apache.maven.api.di.Named;
import org.apache.maven.api.di.Singleton;
import org.apache.maven.api.services.MessageBuilderFactory;
import org.apache.maven.cling.invoker.mvnenc.EncryptContext;
import org.codehaus.plexus.components.secdispatcher.DispatcherMeta;

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

    private PathMappingDbm() {
    }

 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.lifecycle.internal.builder;

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

import java.time.Duration;
import java.time.Instant;
import java.util.List;
import java.util.Set;

import org.apache.maven.api.MonotonicClock;
import org.apache.maven.artifact.Artifact;