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()));

     * Not all sources are backed by files - for example, in-memory sources
     * or database-backed sources will return null.
     *
     * @return the underlying {@code Path} if this source is file-backed,
     *         or {@code null} if this source has no associated file
     */
    @Nullable
    Path getPath();

    /**
     * Creates a new input stream to read the source contents.

        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 null password handling
     */
    @Test
    public void testNullPasswordHandling() {
        // Test with null String password
        NtlmPasswordAuthenticator auth1 = new NtlmPasswordAuthenticator("testuser", (String) null);
        assertNull(auth1.getPassword());

        // Test with null char[] password

        .testEquals();
  }

  @AndroidIncompatible // Android forbids null parent ClassLoader
  public void testClassPathEntries_emptyURLClassLoader_noParent() {
    assertThat(ClassPath.getClassPathEntries(new URLClassLoader(new URL[0], null)).keySet())
        .isEmpty();
  }

  @AndroidIncompatible // Android forbids null parent ClassLoader
  public void testClassPathEntries_urlClassLoader_noParent() throws Exception {

        @Test
        @DisplayName("Should handle null values in toString")
        void testToStringWithNulls() {
            String result = referralData.toString();

            assertTrue(result.contains("server=null"));
            assertTrue(result.contains("share=null"));
            assertTrue(result.contains("link=null"));
            assertTrue(result.contains("path=null"));
        }
    }

    @Nested

    }

    // Test with null configuration values
    public void test_withNullConfigValues() {
        ComponentUtil.setFessConfig(new FessConfig.SimpleImpl() {
            private static final long serialVersionUID = 1L;

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

            @Override

    }

    // Edge/invalid inputs: null or empty share/service cause IllegalArgumentException (mocked)
    @ParameterizedTest
    @DisplayName("getSmbTree invalid inputs (null/empty) throw IllegalArgumentException")
    @CsvSource({ ",service", // null share
            " ,service", // empty share
            "share,", // null service
            "share, " // empty service
    })

            final boolean runAll = webConfigIdList == null && fileConfigIdList == null && dataConfigIdList == null;

            Thread webFsCrawlerThread = null;
            Thread dataCrawlerThread = null;

            if (runAll || webConfigIdList != null || fileConfigIdList != null) {
                webFsCrawlerThread = new Thread((Runnable) () -> {
                    // crawl web

    String stateString = requestUrl.queryParameter("state");
    ByteString state = stateString != null ? ByteString.decodeBase64(stateString) : null;

    Listener listener;
    synchronized (this) {
      listener = listeners.get(state);
    }

    if (code == null || listener == null) {
      return new MockResponse()
          .setResponseCode(404)
          .setBody("unexpected request");
    }