The version number of the object such as node, service, etc. This is needed
to avoid conflicting writes. The client must send the version number along
with the modified specification when updating these objects.
This approach ensures safe concurrency and determinism in that the change
on the object may not be applied if the version number has changed from the
last read. In other words, if two update requests specify the same base
version, only one of the requests can succeed. As a result, two separate
update requests that happen at the same time will not unintentionally
overwrite each other.