* value is undefined.
     *
     * @return The location of the problem, never {@code null}.
     */
    String getLocation();

    /**
     * Gets the exception that caused this problem (if any).
     *
     * @return The exception that caused this problem or {@code null} if not applicable.
     */
    Exception getException();

    /**
     * Gets the message that describes this problem.

        Metadata repoMetadata = metadata.getMetadata();
        String version = null;
        if (repoMetadata != null && repoMetadata.getVersioning() != null) {
            version = constructVersion(repoMetadata.getVersioning(), artifact.getBaseVersion());
        }

        if (version == null) {
            // use the local copy, or if it doesn't exist - go to the remote repo for it

        // Test with null source array
        dest = new byte[8];
        nextOffset = NtlmMessage.writeSecurityBuffer(dest, 0, null);
        assertEquals(4, nextOffset, "Should return correct next offset for null source.");
        assertEquals(0, NtlmMessage.readUShort(dest, 0), "Length should be 0 for null source.");

     * @param url the URL to convert
     * @return the converted URL after applying all duplicate host rules,
     *         or null if the input URL is null
     */
    public String convert(final String url) {
        if (url == null) {
            return null;
        }

        if (duplicateHostList == null) {
            init();
        }

        String newUrl = url;

        if (classpath == null || classpath.isEmpty()) {
            return null;
        }

        MetadataTreeNode tree = null;
        MetadataTreeNode parent = null;

        for (ArtifactMetadata md : classpath) {
            MetadataTreeNode node = new MetadataTreeNode(md, parent, md.isResolved(), md.getArtifactScope());
            if (tree == null) {
                tree = node;
            }

        .build(),
    )
    val source = newEventSource()
    assertThat(source.request().url.encodedPath).isEqualTo("/")
    listener.assertOpen()
    listener.assertEvent(null, null, "hey")
    listener.assertClose()
  }

  @RetryingTest(5)
  fun cancelInEventShortCircuits() {
    server.enqueue(
      MockResponse
        .Builder()
        .body(
          """

  private val key: String

  /** Non-null for client web sockets. These can be canceled. */
  internal var call: Call? = null

  /** This task processes the outgoing queues. Call [runWriter] to after enqueueing. */
  private var writerTask: Task? = null

  /** Null until this web socket is connected. Only accessed by the reader thread. */
  private var reader: WebSocketReader? = null

        }
    }

    // Test property filter returning null simulation
    public void test_get_filterReturnsNull() {
        // The filter.null property is configured to simulate null filter behavior
        try {
            fessConfig.get("filter.null");
            fail("Should throw exception when property is not found");
        } catch (ConfigPropertyNotFoundException e) {

    @Test
    @DisplayName("Test equals method with null netName")
    void testEqualsWithNullNetName() {
        SmbShareInfo info1 = new SmbShareInfo();
        SmbShareInfo info2 = new SmbShareInfo();

        // Both have null netName
        assertTrue(info1.equals(info2));

        SmbShareInfo info3 = new SmbShareInfo(TEST_NET_NAME, 0, TEST_REMARK);
        // One null, one non-null
        assertFalse(info1.equals(info3));

     * allowing the CAS below to succeed.
     */
    Thread currentThread = Thread.currentThread();
    if (!compareAndSet(null, currentThread)) {
      return; // someone else has run or is running.
    }

    boolean run = !isDone();
    T result = null;
    Throwable error = null;
    try {
      if (run) {
        result = runInterruptibly();