Resolution
Inbound agent connections are initiated by the agent, so a controller does not manage them in general.
Thus the retention strategy that must be selected when configuring the agent is:
Keep this agent online as much as possible
Choosing any other strategy does not make sense, since if the selected retention strategy were:
Take this agent online when in demand, and offline when idle
the agent will then re-establish the connection. And if the retention strategy:
Take this agent online according to a schedule
is selected, the JNLP agent connection will be terminated by the Jenkins master according to the schedule, but the agent will then re-establish the connection.
In both invalid cases, and specially if the JNLP command is installed as a service, the logs will grow excessively.