code: public Attributes getMainAttributes() throws IOException {
          Manifest man = getManifest();
          return man != null ? man.getMainAttributes() : null;
      }
docs: Returns the main Attributes for the JAR file for this
  connection.
  
  @return the main Attributes for the JAR file for this
  connection.
  
  @exception IOException if getting the manifest causes an
  IOException to be thrown.
  
  @see #getJarFile
  @see #getManifest