if (keyList == null || keyList.isEmpty()) {
            throw new CrawlerSystemException("The key list is empty.");
        }
        keyList.stream().distinct().forEach(key -> addExtractor(key, extractor));
    }

    /**
     * Retrieves an extractor for the specified key.
     * If multiple extractors are associated with the key, returns a composite extractor

import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

import org.codelibs.fess.crawler.entity.OpenSearchUrlFilter;
import org.codelibs.fess.crawler.exception.CrawlerSystemException;
import org.codelibs.fess.crawler.service.UrlFilterService;

        try {
            final ExtractData extractData = new ExtractData(
                    StreamUtil.stream(getStringsByXPath(document, contentXpath)).get(stream -> stream.collect(Collectors.joining(" "))));
            metadataXpathMap.entrySet().stream().forEach(e -> {
                extractData.putValues(e.getKey(), getStringsByXPath(document, e.getValue()));
            });
            return extractData;

            return mimeTypeHelper.getContentType(is, filename);
        }
    }

    /**
     * Gets an input stream for the content in the deferred file output stream.
     *
     * @param out the deferred file output stream
     * @return the input stream for the content
     * @throws IOException if an I/O error occurs
     */

            final Stream<QueryLog> stream = Stream.of(queryLogs);
            if (parallel) {
                stream.parallel();
            }
            final SuggestItem[] array = stream.flatMap(queryLog -> contentsParser
                    .parseQueryLog(queryLog, supportedFields, tagFieldNames, roleFieldName, readingConverter, normalizer)
                    .stream()).toArray(n -> new SuggestItem[n]);

        return new ExtractData(getTextInternal(in, mimeTypeHelper, extractorFactory));
    }

    /**
     * Returns a text from the input stream.
     *
     * @param in The input stream.
     * @param mimeTypeHelper The mime type helper.
     * @param extractorFactory The extractor factory.
     * @return A text.
     */

        assertContentType("application/xml", "extractor/test.mm", "hoge.mm");

        assertContentType("message/rfc822", "extractor/eml/sample1.eml", "sample1.eml");

        assertContentType("application/octet-stream", null, "hoge");

        assertContentType("application/vnd.ms-powerpoint", "extractor/msoffice/test.ppt", "h&oge.ppt");
        assertContentType("application/vnd.ms-powerpoint", "extractor/msoffice/test.ppt", "h?oge.ppt");

 *
 * <p>All other methods delegate to the wrapped input stream.</p>
 *
 */
public class IgnoreCloseInputStream extends InputStream {

    /** The wrapped input stream. */
    private transient InputStream inputStream;

    /**
     * Constructs a new IgnoreCloseInputStream that wraps the specified input stream.
     *

 */
package org.codelibs.fess.crawler.filter.impl;

import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.fess.crawler.container.CrawlerContainer;
import org.codelibs.fess.crawler.exception.CrawlerSystemException;

    /**
     * Creates a new MsVisioExtractor instance.
     */
    public MsVisioExtractor() {
        super();
    }

    /**
     * Extracts text from the Visio input stream.
     * @param in The input stream.
     * @param params The parameters.
     * @return The extracted data.
     */
    @Override
    public ExtractData getText(final InputStream in, final Map<String, String> params) {