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

    private BoostDocumentRuleDbm() {
    }

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

    private JobLogDbm() {
    }

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

    private WebConfigDbm() {
    }

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

    private FileAuthenticationDbm() {
    }

        }
      }

      Control control = new Control();
      Hasher controlSink = control.newHasher(1024);

      Iterable<Hasher> sinksAndControl =
          Iterables.concat(sinks, Collections.singleton(controlSink));
      for (int insertion = 0; insertion < totalInsertions; insertion++) {
        RandomHasherAction.pickAtRandom(random).performAction(random, sinksAndControl);
      }

        new Target(MinimalCollection.of(e0(), e0(), e3(), e3()), "containsDuplicates");
    partialOverlap = new Target(MinimalCollection.of(e2(), e3()), "partialOverlap");
    nullSingleton = new Target(Collections.<E>singleton(null), "nullSingleton");
  }

  // retainAll(empty)

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  @CollectionSize.Require(ZERO)
  public void testRetainAll_emptyPreviouslyEmpty() {

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

    private AccessTokenDbm() {
    }

      new ImmutableClassToInstanceMap<>(ImmutableMap.<Class<?>, Object>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;
  }

  /**

                    .authority(authority)
                    .build();

            final RefreshTokenParameters parameters =
                    RefreshTokenParameters.builder(Collections.singleton("https://graph.microsoft.com/.default"), refreshToken).build();

            final IAuthenticationResult result = app.acquireToken(parameters).get(acquisitionTimeout, TimeUnit.MILLISECONDS);
            if (result == null) {

import static com.google.common.truth.Truth.assertThat;
import static java.util.Arrays.asList;
import static java.util.Collections.emptyList;
import static java.util.Collections.emptySet;
import static java.util.Collections.singleton;
import static java.util.Collections.singletonList;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;