Moquette deeply nested MQTT topics can cause stack exhaustion

Moquette is a lightweight Java MQTT broker. Prior to 0.18.1, Moquette does not limit the depth of topic names and topic filters before processing them through recursive CTrie insertion and matching operations. A remote client can publish or subscribe with a deeply nested topic, causing a StackOverflowError that disrupts session processing and can deny service to broker clients. This issue is fixed in version 0.18.1.