@Override
    public void postInitialize(String configId) {
        super.postInitialize(configId);
        if (":parent:".equals(value()))  {
            doSetValue(configId);
        }
    }
Overrides {@link Node#postInitialize(String)}
Checks for ":parent:" values, which will be replaced by the configId.

@param configId  the configId of the ConfigInstance that owns (or is) this node
config-lib/src/main/java/com/yahoo/config/ReferenceNode.java