public String toString() {
    return "ServerQueueStatus [" + "queueSize=" + qSize
        + "; endpointType=" + getTypeAsString() + "; pingInterval="
        + pingInterval + "ms]";
  }
returns the time between server-to-client ping messages on idle subscription connections
geode-core/src/main/java/org/apache/geode/internal/cache/tier/sockets/ServerQueueStatus.java