*
 * <p>
 * The factory maintains a map of keys to an array of {@link Extractor} objects.
 * When multiple extractors are associated with a single key, they are sorted by weight
 * in descending order. The {@link #getExtractor(String)} method returns a composite
 * extractor that iterates through the available extractors until one successfully
 * extracts the data.
 * </p>
 *
 * <p>

	<dd>
		sort field sorts documents by a specified field name. The format is
		"sort:&lt;field&gt;.&lt;order&gt;", where &lt;order&gt; is asc or
		desc. If you want to find documents which has "Fess" and sort them in
		descending order, you can enter:
		<pre>Fess sort:content_length.desc</pre>
		The available sort field are "created", "content_length" and
		"last_modified", and they are customizable.
	</dd>
	<dt>AND</dt>
	<dd>