This allows us to associate an observation from the log
for messages that the local node did not observe.
Change-Id: I6ece7bfe3e6b878bdb7ee4ac03c81cb424a329b3
Optional metadata for debugging. Allows tying a received observation
to an on-chain transaction even if the node missed the observation.
Change-Id: Ie50c10c8ab7f65469555674d90645f91092fb2e3