}

    /**
     * Extracts metadata from the PDF document and adds it to the extraction result.
     * @param document the PDF document
     * @param extractData the extraction data to add metadata to
     */
    protected void extractMetadata(final PDDocument document, final ExtractData extractData) {
        final PDDocumentInformation info = document.getDocumentInformation();
        if (info == null) {
            return;

            });
            return extractData;
        } finally {
            xpathAPI.remove();
        }
    }

    /**
     * Extracts strings from a document using the specified XPath expression.
     *
     * @param document the DOM document to extract strings from
     * @param path the XPath expression to evaluate

            ReadingConverter readingConverter, Normalizer normalizer);

    /**
     * Parses a document and extracts suggest items based on the provided fields and converters.
     *
     * @param document The document to parse, represented as a map of field names to values.
     * @param fields The fields to extract from the document.
     * @param tagFieldNames The names of the fields that contain tags.

 */
package org.codelibs.fess.suggest.index.contents.document;

import java.io.Closeable;
import java.util.Map;

/**
 * Interface for reading documents and extracting their contents into a map.
 * Implementations of this interface should provide the logic for reading
 * documents and converting them into a key-value structure.
 *

 * reader.setScrollSize(1000); // Set the scroll size
 * reader.setLimitOfDocumentSize(1024 * 1024); // Limit document size to 1MB
 * reader.setQuery(QueryBuilders.termQuery("field", "value")); // Set a query
 *
 * Map<String, Object> document;
 * while ((document = reader.read()) != null) {
 *     // Process the document
 *     System.out.println(document);
 * }
 *
 * reader.close(); // Close the reader to release resources
 * }
 * </pre>
 */

        String field = settings.array().get(SuggestSettings.DefaultKeys.SUPPORTED_FIELDS)[0];

        Map<String, Object> document = new HashMap<>();
        document.put(field, "The persimmon is delicious");
        document.put("lang", "en");
        suggester.indexer().indexFromDocument(new Map[] { document });
        suggester.refresh();

        }
        return tokens;
    }

    /**
     * Get field values.
     * @param document Document
     * @param fieldName Field name
     * @return Field values
     */
    protected String[] getFieldValues(final Map<String, Object> document, final String fieldName) {
        final Object value = document.get(fieldName);
        if (value instanceof String) {
            return new String[] { value.toString() };

    }

    /**
     * Returns the additional data for the response.
     * @param responseData The response data.
     * @param document The document.
     * @return The additional data.
     */
    protected String getAdditionalData(final ResponseData responseData, final Document document) {
        return "";
    }

    /**
     * Returns the result data footer.
     * @return The result data footer.
     */

    }

    /**
     * Indexes documents from an array of maps.
     * @param documents The documents to index.
     * @return The SuggestIndexResponse.
     */
    public SuggestIndexResponse indexFromDocument(final Map<String, Object>[] documents) {
        final long start = System.currentTimeMillis();
        try {
            final Stream<Map<String, Object>> stream = Stream.of(documents);
            if (parallel) {

```

## Advanced Usage

### Index from Existing Documents

```java
import org.codelibs.fess.suggest.index.contents.document.ESSourceReader;

// Index suggestions from existing Elasticsearch documents
DocumentReader reader = new ESSourceReader(
    client,
    suggester.settings(),
    "content-index",        // source index
    "document"             // document type
);

suggester.indexer()