Description

Currently, the timestamp field of the TransitionEvent message is a uint64, which should be interpreted as a Unix timestamp.
However, most ROS interfaces use builtin_interfaces/msg/Time to represent the time.

Motivation

This would make the timestamp of the transition event easier to work with, since it would work with the preexisting tools for other messages.

Design / Implementation Considerations

The message would not change size (disregarding padding).

Currently this timestamp is not being filled by rcl_lifecycle (ros2/rcl#1019), so there is very little tooling directly affected.

Additional Information

Is there a technical reason why this is a normal Unix timestamp instead of a builtin_interfaces/msg/Time?

I would be able to make the pull request.

EDIT: Extra additional information