code: public Collection<? extends java.security.cert.CRL> engineGenerateCRLs(
              InputStream is) throws CRLException
      {
          if (is == null) {
              throw new CRLException("Missing input stream");
          }
          try {
              return parseX509orPKCS7CRL(is);
          } catch (IOException ioe) {
              throw new CRLException(ioe.getMessage());
          }
      }
docs: Returns a (possibly empty) collection view of X.509 CRLs read
  from the given input stream <code>is</code>.
  
  @param is the input stream with the CRLs.
  
  @return a (possibly empty) collection view of X.509 CRL objects
  initialized with the data from the input stream.
  
  @exception CRLException on parsing errors.