Field confDataMapField = GlobalConfiguration.class.getDeclaredField("confData");
singletonInstanceField.setAccessible(true);
confDataMapField.setAccessible(true);
GlobalConfiguration gconf = (GlobalConfiguration) singletonInstanceField.get(null);
if (gconf != null) {
@SuppressWarnings("unchecked")
Map<String, String> confData = (Map<String, String>) confDataMapField.get(gconf);
confData.clear();
}