* <b>Usage:</b>
 * </p>
 * <pre>
 * {@code
 * Client client = // Obtain Elasticsearch client
 * SuggestSettings settings = // Obtain SuggestSettings
 * String indexName = "your_index_name";
 *
 * ESSourceReader reader = new ESSourceReader(client, settings, indexName);
 * reader.setScrollSize(1000); // Set the scroll size
 * reader.setLimitOfDocumentSize(1024 * 1024); // Limit document size to 1MB

    }

    @Test
    public void test_getLimitDocNum() throws Exception {
        assertEquals(10, ESSourceReader.getLimitDocNum(100, 10, -1));
        assertEquals(25, ESSourceReader.getLimitDocNum(50, 50, -1));
        assertEquals(10, ESSourceReader.getLimitDocNum(50, 50, 10));
    }

    @Test
    public void test_sort() throws Exception {
        String indexName = "test-index";

    });
```

## 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
);

        final SystemHelper systemHelper = ComponentUtil.getSystemHelper();
        suggester.indexer().indexFromDocument(() -> {
            final ESSourceReader reader = new ESSourceReader(ComponentUtil.getSearchEngineClient(), suggester.settings(),
                    fessConfig.getIndexDocumentSearchIndex());
            reader.setScrollSize(fessConfig.getSuggestSourceReaderScrollSizeAsInteger());

        bulkRequestBuilder.execute().actionGet();
        runner.refresh();

        CountDownLatch latch = new CountDownLatch(1);
        AtomicInteger numObInputDoc = new AtomicInteger(0);
        ESSourceReader reader = new ESSourceReader(client, suggester.settings(), indexName);
        reader.setScrollSize(1000);

        suggester.indexer().indexFromDocument(() -> reader, 1000, () -> ThreadUtil.sleep(100)).then(response -> {