OptionalbodyOptional message.
Additional information attached to this message.
Header values must be JSON serializable. If no headers are set, the Map is empty.
OptionalparamsContains the resolved values of the wildcard segments as specified in the topic.
For example: If subscribed to the topic person/:id and a message is published to the topic person/5,
the resolved id with the value 5 is contained in the params map.
OptionalretainIndicates whether this message is retained on the broker for late subscribers.
The topic where to publish this message to.
Represents a message published to a topic.
The message is transported to all consumers subscribed to the topic.