code: private void matchX509CRLs(CRLSelector selector, Collection<CRL> matches) {
          for (Object obj : crlIssuers.values()) {
              if (obj instanceof X509CRL) {
                  X509CRL crl = (X509CRL)obj;
                  if (selector.match(crl)) {
                      matches.add(crl);
                  }
              } else {
                  // See crlIssuers javadoc.
                  @SuppressWarnings("unchecked")
                  List<X509CRL> list = (List<X509CRL>)obj;
                  for (X509CRL crl : list) {
                      if (selector.match(crl)) {
                          matches.add(crl);
                      }
                  }
              }
          }
      }
docs: Iterate through all the X509CRLs and add matches to the
  collection.