@Override
  public String toString() {
    return "TimelineAppMetricCacheKey{" +
      "metricNames=" + metricNames +
      ", appId='" + appId + '\'' +
      ", hostNames=" + hostNames +
      ", spec='" + spec + '\'' +
      '}';
  }
Set spec string.
@param spec Request Uri
ambari-server/src/main/java/org/apache/ambari/server/controller/metrics/timeline/cache/TimelineAppMetricCacheKey.java