return higher;
      }
    }
    return null;
  }

  public @Nullable E ceiling(E e) {
    ImmutableSortedSet<E> set = tailSet(e, true);
    return !set.isEmpty() ? set.first() : null;
  }

  public @Nullable E floor(E e) {
    ImmutableSortedSet<E> set = headSet(e, true);
    return !set.isEmpty() ? set.last() : null;
  }

                "test-grp", "test-artifact", VersionRange.createFromVersion("1.0"), "type", null, "system", "provided");
        Artifact artifact2 = factory.createDependencyArtifact(
                "test-grp", "test-artifact-2", VersionRange.createFromVersion("1.0"), "type", null, "system", "test");
        Artifact artifact3 = factory.createDependencyArtifact(
                "test-grp",

    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }

        if (MetadataGraphNode.class.isAssignableFrom(obj.getClass())) {
            MetadataGraphNode node2 = (MetadataGraphNode) obj;

            if (node2.metadata == null) {
                return metadata == null;
            }

            return metadata != null && metadata.toString().equals(node2.metadata.toString());

@Deprecated
public class TestRepositorySystem implements RepositorySystem {

    private final ModelReader modelReader;

    private final ArtifactFactory artifactFactory;

    public TestRepositorySystem() {
        this(null, null);
    }

    @Inject
    public TestRepositorySystem(ModelReader modelReader, ArtifactFactory artifactFactory) {
        this.modelReader = modelReader;
        this.artifactFactory = artifactFactory;
    }

  public void testAddAllAtIndex_nullSupported() {
    List<E> containsNull = singletonList(null);
    assertTrue("addAll(n, containsNull) should return true", getList().addAll(0, containsNull));
    /*
     * We need (E) to force interpretation of null as the single element of a
     * varargs array, not the array itself
     */
    expectAdded(0, (E) null);
  }

  @ListFeature.Require(SUPPORTS_ADD_WITH_INDEX)

    initMapWithNullValue();

    getMap().forcePut(k1(), null);

    expectContents(mapEntry(k1(), (V) null));

    assertFalse(getMap().containsKey(k0()));

    assertTrue(getMap().containsKey(k1()));
    assertTrue(getMap().inverse().containsKey(null));
    assertNull(getMap().get(k1()));
    assertEquals(k1(), getMap().inverse().get(null));
    assertEquals(1, getMap().size());
  }

    int initialSize = collection.size();
    assertTrue("remove(null) should return true", collection.remove(null));
    assertEquals(
        "remove(present) should decrease a collection's size by one.",
        initialSize - 1,
        collection.size());
    expectMissing((E) null);
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)

    }

    @Override
    public @Nullable Integer next(Integer value) {
      int i = value;
      return (i == Integer.MAX_VALUE) ? null : i + 1;
    }

    @Override
    public @Nullable Integer previous(Integer value) {
      int i = value;
      return (i == Integer.MIN_VALUE) ? null : i - 1;
    }

    @Override
    Integer offset(Integer origin, long distance) {
      checkNonnegative(distance, "distance");

   * removal operations, and these are reflected in the underlying map.
   *
   * <p>It's acceptable for the underlying map to contain null keys, and even null values provided
   * that the function is capable of accepting null input. The transformed map might contain null
   * values, if the function sometimes gives a null result.
   *
   * <p>The returned map is not thread-safe or serializable, even if the underlying map is.
   *

   * removal operations, and these are reflected in the underlying map.
   *
   * <p>It's acceptable for the underlying map to contain null keys, and even null values provided
   * that the function is capable of accepting null input. The transformed map might contain null
   * values, if the function sometimes gives a null result.
   *
   * <p>The returned map is not thread-safe or serializable, even if the underlying map is.
   *