if (predecessors != null) {
      checkState(predecessors.remove(node));
    }
    return node;
  }

  @Override
  public N removeOutEdge(E edge) {
    N node = super.removeOutEdge(edge);
    Multiset<N> successors = getReference(successorsReference);
    if (successors != null) {
      checkState(successors.remove(node));
    }
    return node;
  }

    if (predecessors != null) {
      checkState(predecessors.remove(node));
    }
    return node;
  }

  @Override
  public N removeOutEdge(E edge) {
    N node = super.removeOutEdge(edge);
    Multiset<N> successors = getReference(successorsReference);
    if (successors != null) {
      checkState(successors.remove(node));
    }
    return node;
  }

        assertNotNull(avFlags, "AvFlags object should not be null");
        assertEquals(0x04030201, avFlags.getFlags(), "Flags should match the raw bytes (little-endian)");

        // Test with zero
        byte[] zeroBytes = new byte[] { 0x00, 0x00, 0x00, 0x00 };
        AvFlags zeroAvFlags = new AvFlags(zeroBytes);
        assertNotNull(zeroAvFlags, "AvFlags object should not be null for zero bytes");

        assertEquals("0.0.0.0", unknownName.getName(), "Unknown name should be 0.0.0.0");
    }

    @Test
    @DisplayName("Should handle null hostname in getByName")
    void testGetByNameWithNull() {
        // When/Then
        assertThrows(UnknownHostException.class, () -> {
            nameServiceClient.getByName(null);

        return LegacyLocalRepositoryManager.overlay(localRepository, legacySupport.getRepositorySession(), null);
    }

    private void injectSession1(RepositoryRequest request, MavenSession session) {
        if (session != null) {
            request.setOffline(session.isOffline());
            request.setForceUpdate(session.getRequest().isUpdateSnapshots());
        }
    }

     * @return map of attribute names to values, never {@code null}
     */
    @Nonnull
    Map<String, String> attributes();

    /**
     * Returns the value of a specific attribute.
     *
     * @param name the name of the attribute to retrieve
     * @return the attribute value, or {@code null} if the attribute doesn't exist
     * @throws NullPointerException if name is null
     */
    @Nullable

     * @param key       The key associated with the extractor. Must not be null or blank.
     * @param extractor The extractor to add. Must not be null.
     */
    public void addExtractor(final String key, final Extractor extractor) {
        if (StringUtil.isBlank(key)) {
            throw new CrawlerSystemException("The key is null.");
        }
        if (extractor == null) {
            throw new CrawlerSystemException("The extractor is null.");

        DialectVersion selected = null;
        for (final DialectVersion dv : DialectVersion.values()) {
            if (!dv.isSMB2()) {
                continue;
            }
            if (dv.getDialect() == getDialectRevision()) {
                selected = dv;
            }
        }

        if (selected == null) {
            log.debug("Server returned an unknown dialect");

        // Test with null value
        ComponentUtil.setFessConfig(new FessConfig.SimpleImpl() {
            private static final long serialVersionUID = 1L;

            @Override
            public String getApiJsonResponseExceptionIncluded() {
                return null;
            }
        });

        assertThat(ClassUtil.concatName("aaa", null), is("aaa"));
        assertThat(ClassUtil.concatName("aaa", ""), is("aaa"));
        assertThat(ClassUtil.concatName(null, "bbb"), is("bbb"));
        assertThat(ClassUtil.concatName("", "bbb"), is("bbb"));
        assertThat(ClassUtil.concatName("", "bbb"), is("bbb"));
        assertThat(ClassUtil.concatName(null, null), is(nullValue()));