getSetting(key) {
        const flow = this.flow;
        if (key === "NR_FLOW_NAME") {
            return flow.label;
        }
        if (key === "NR_FLOW_ID") {
            return flow.id;
        }
        if (!key.startsWith("$parent.")) {
            if (this._env.hasOwnProperty(key)) {
                return (this._env[key] && Object.hasOwn(this._env[key], 'value') && this._env[key].__clone__) ? clone(this._env[key].value) : this._env[key]
            }
        } else {
                key = key.substring(8);
        }
        // Delegate to the parent flow.
        return this.parent.getSetting(key);
    }
Get a flow setting value.
@param  {[type]} key [description]
@return {[type]}     [description]