public ClientCacheFactory setPoolSubscriptionMessageTrackingTimeout(int messageTrackingTimeout) {
    getPoolFactory().setSubscriptionMessageTrackingTimeout(messageTrackingTimeout);
    return this;
  }
Sets the messageTrackingTimeout attribute which is the time-to-live period, in milliseconds,
for subscription events the client has received from the server. It's used to minimize
duplicate events. Entries that have not been modified for this amount of time are expired from
the list

@param messageTrackingTimeout number of milliseconds to set the timeout to.
@return a reference to <code>this</code>
@throws IllegalArgumentException if <code>messageTrackingTimeout</code> is less than or equal
        to <code>0</code>.
geode-core/src/main/java/org/apache/geode/cache/client/ClientCacheFactory.java