archaius-core/src/main/java/com/netflix/config/DynamicProperty.java
private static boolean updateProperty(String propName, Object value) {
        DynamicProperty prop = ALL_PROPS.get(propName);
        if (prop != null && prop.updateValue(value)) {
            prop.notifyCallbacks();
            return true;
        }
        return false;
    }
private static boolean updateProperty(String propName, Object value) {
        DynamicProperty prop = ALL_PROPS.get(propName);
        if (prop != null && prop.updateValue(value)) {
            prop.notifyCallbacks();
            return true;
        }
        return false;
    }
return true iff the value actually changed