});
```

## 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
);

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
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

import org.codelibs.fess.suggest.index.contents.ContentsParser;
import org.codelibs.fess.suggest.index.contents.DefaultContentsParser;
import org.codelibs.fess.suggest.index.contents.document.DocumentReader;
import org.codelibs.fess.suggest.index.contents.querylog.QueryLog;
import org.codelibs.fess.suggest.index.contents.querylog.QueryLogReader;
import org.codelibs.fess.suggest.index.writer.SuggestIndexWriter;

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,

        this.index = index;
        this.tookMs = tookMs;
        this.words = words;
        num = words.size();
        this.total = total;
        this.items = items;
    }

    /**
     * Returns the index associated with the response.
     *
     * @return the index
     */
    public String getIndex() {
        return index;
    }

    /**

 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.suggest.index.writer;

import org.codelibs.fess.suggest.entity.SuggestItem;
import org.codelibs.fess.suggest.settings.SuggestSettings;
import org.opensearch.index.query.QueryBuilder;
import org.opensearch.transport.client.Client;

/**

        final Map<String, Object> firstLineInnerMap = new HashMap<>();
        firstLineInnerMap.put("_index", index);
        firstLineInnerMap.put("_type", type);
        firstLineInnerMap.put("_id", item.getId());
        firstLineMap.put("index", firstLineInnerMap);

        final Map<String, Object> secondLine = new HashMap<>();

        secondLine.put("text", item.getText());

        // reading

/*
 * Copyright 2012-2025 CodeLibs Project and the Others.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,