code: private static Configuration append(Configuration base, Configuration additional) {
  		final CompositeConfiguration result = new CompositeConfiguration();
  		result.addConfiguration(additional);
  		result.addConfiguration(base);
  		return result;
  	}
docs: Takes two configuration and returns their union, with the second overriding the first.
  
  @param base the base configuration.
  @param additional the additional set of properties, some of which may override those specified in <code>base</code>.
  @return the union of the two configurations, as specified above.