public boolean isMetricsServiceRequestTTLCacheEnabled() {
    return Boolean.parseBoolean(getProperty(METRIC_RETRIEVAL_SERVICE_REQUEST_TTL_ENABLED));
  }
Gets whether the TTL request cache in the {@link MetricsRetrievalService}
is enabled. This evicting cache is used to prevent requests to the same URL
within a specified amount of time.

@return {@code true} if enabled, {@code false} otherwise.
ambari-server/src/main/java/org/apache/ambari/server/configuration/Configuration.java