code: private static String getXtextKey(String preferenceContainerID, String preferenceName) {
  		return GENERATOR_PREFERENCE_TAG + PreferenceConstants.SEPARATOR + preferenceContainerID
  				+ PreferenceConstants.SEPARATOR + preferenceName;
  	}
docs: Create a preference key according to the Xtext option block standards.
  
  @param preferenceContainerID the identifier of the generator's preference container.
  @param preferenceName the name of the preference.
  @return the key.