public Builder<T> setBaseClass(final Class<?> baseClass) {
            if(clazz != Class.class) {
                throw new IllegalArgumentException("Only properties of type Class can have a base class set");
            }
            this.baseClass = baseClass;
            return this;
        }
This indicates which class configured values must inherit from. It must be set (and can only be set) if the default
value is a class.

@param baseClass - the base class from which all configured values must inherit
@return The current SystemProperty builder
xmppserver/src/main/java/org/jivesoftware/util/SystemProperty.java