- [Apache Solr](#apache-solr)
  - [Other Search Systems](#other-search-systems)
- [Data Import Methods](#data-import-methods)
- [Configuration Migration](#configuration-migration)
- [API Reference](#api-reference)
- [Troubleshooting](#troubleshooting)
- [Migration Checklist](#migration-checklist)

---

## Supported Migration Sources

Fess provides built-in support and compatibility layers for:

# Sorts for inner hits in collapse queries.
query.collapse.inner.hits.sorts=
# Default languages for queries.
query.default.languages=
# Default preference for JSON queries.
query.json.default.preference=_query
# Default preference for GSA queries.
query.gsa.default.preference=_query
# Language mapping for queries.
query.language.mapping=\
ar=ar\n\
bg=bg\n\
bn=bn\n\
ca=ca\n\
ckb-iq=ckb-iq\n\
ckb_IQ=ckb-iq\n\

    public static final String REQUEST_LANGUAGES = "requestLanguages";

    /** Request page size parameter name. */
    public static final String REQUEST_PAGE_SIZE = "requestPageSize";

    /** Search preference for local node. */
    public static final String SEARCH_PREFERENCE_LOCAL = "_local";

    /** GSA API version identifier. */
    public static final String GSA_API_VERSION = "3.2";

     * Get the value for the key 'query.json.default.preference'. <br>
     * The value is, e.g. _query <br>
     * comment: Default preference for JSON queries.
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getQueryJsonDefaultPreference();

    /**
     * Get the value for the key 'query.gsa.default.preference'. <br>
     * The value is, e.g. _query <br>

        msg.addSource(new ChatSource(2, doc2));

        final String result = chatClient.testBuildAssistantHistoryContent(msg, "source_titles", 500, 500);
        assertEquals("Response text\n[Referenced documents: Installation Guide, Quick Start]", result);
    }

    @Test
    public void test_buildAssistantHistoryContent_sourceTitles_withoutSources() {

        this.timestamp = timestamp;
    }

    /**
     * Gets the list of sources referenced in the message.
     *
     * @return the list of sources
     */
    public List<ChatSource> getSources() {
        return sources;
    }

    /**
     * Sets the list of sources referenced in the message.
     *
     * @param sources the list of sources
     */

        assertEquals("processed_site1", result); // Still site1 due to header precedence

        // Test with custom header
        request.addHeader("Custom-Header", "custom.value");
        result = virtualHostHelper.processVirtualHost(s -> "processed_" + s, "default");
        assertEquals("processed_site1", result); // Still site1 due to header precedence
    }

    @Test

        assertTrue(exception1.getCause() instanceof java.io.IOException);

        StorageException exception2 = new StorageException("NPE", new NullPointerException("Null reference"));
        assertTrue(exception2.getCause() instanceof NullPointerException);

        StorageException exception3 = new StorageException("Custom", new FessSystemException("System error"));

        final Element root = webXmlDocument.getDocumentElement();
        final String schemaLocation = root.getAttributeNS("http://www.w3.org/2001/XMLSchema-instance", "schemaLocation");
        assertTrue("schemaLocation should reference web-app_6_1.xsd", schemaLocation.contains("web-app_6_1.xsd"));
    }

     * Builds a summary string from source document titles.
     *
     * @param msg the assistant chat message
     * @param summaryMaxChars the maximum characters for the content summary
     * @return a string listing referenced document titles
     */
    protected String buildSourceTitlesContent(final ChatMessage msg, final int summaryMaxChars) {
        final List<ChatSource> sources = msg.getSources();