* This method manages local caches and fetches from OpenSearch when needed.
     *
     * @param sessionId The session ID.
     * @return The next URL queue entry, or null if none available.
     */
    @Override
    public OpenSearchUrlQueue poll(final String sessionId) {
        final QueueHolder queueHolder = getQueueHolder(sessionId);

     * @return the embedded file, or null if not found
     */
    protected PDEmbeddedFile getEmbeddedFile(final PDComplexFileSpecification fileSpec) {
        // search for the first available alternative of the embedded file
        PDEmbeddedFile embeddedFile = null;
        if (fileSpec != null) {
            embeddedFile = fileSpec.getEmbeddedFileUnicode();
            if (embeddedFile == null) {

        <match value="facet " offset="7:256" type="string"/>
      </match>
    </magic>
  </mime-type>
  <mime-type type="model/x.stl-binary">
    <_comment>no magic available</_comment>
    <glob pattern="*.stl"/>
  </mime-type>
  <mime-type type="model/vnd.dwf">
    <acronym>DWF</acronym>
    <_comment>AutoCAD Design Web Format</_comment>
    <alias type="drawing/x-dwf"/>