private void mergeValues( List<String> valuesFromSource, ConfigurationProperty p, List<String> vals) { switch (p.getPropertySourceMode()) { case APPEND: vals.addAll(valuesFromSource); break; case OVERRIDE: vals.clear(); vals.addAll(valuesFromSource); break; default: throw new UnsupportedOperationException("Unknown source mode " + p.getPropertySourceMode()); } }