add support to get instance creation datetime from compute api (NodeMetadata? )

[hackndoes]

There is a need to get the creation datetime of an instance using the compute api for generic cross cloud provider support.

[demobox]

Note that for e.g. EC2 RunningInstance already has launchTime information. Initial questions from me would be:

• which clouds specifically do you need this information for?
• for these clouds, is the information available via the provider-specific domain objects already?
• for how many clouds is this information not currently available in the provider domain logic?

[abayer]

fwiw, I tend to think this is worthwhile - EC2, OpenStack Nova and CloudStack all have a launch time (or created time) field. It would need to be Nullable, given how many of the other APIs don't have it (i.e., vcloud, byon, cloudservers...), but it seems reasonable to add it to NodeMetadata when possible.

[demobox]

EC2, OpenStack Nova and CloudStack all have a launch time

Seems like the current "big guns", indeed... ;-)

Do we do @Nullable launchTime or Optional<...> launchTime in NodeMetadata nowadays? @adriancole ?

[codefromthecrypt]

I could go either way since the class already has nullable fields.
Personally, I prefer Optional.