code: public Enumeration<String> getElements() {
          AttributeNameEnumeration elements = new AttributeNameEnumeration();
          elements.addElement(DIGITAL_SIGNATURE);
          elements.addElement(NON_REPUDIATION);
          elements.addElement(KEY_ENCIPHERMENT);
          elements.addElement(DATA_ENCIPHERMENT);
          elements.addElement(KEY_AGREEMENT);
          elements.addElement(KEY_CERTSIGN);
          elements.addElement(CRL_SIGN);
          elements.addElement(ENCIPHER_ONLY);
          elements.addElement(DECIPHER_ONLY);
  
          return (elements.elements());
      }
docs: Return an enumeration of names of attributes existing within this
  attribute.