SuppressWarnings("serial") for starter and example archetypes

[kennknowles]

The usual case for using Beam is that every user DoFn, etc, is serialized with autogenerated serialVersionUID. Our starter and example archetypes should reflect this, so when someone loads them up in an IDE they are not presented with warning-throwing code.

Imported from Jira BEAM-1254. Original Jira may contain additional context.
Reported by: kenn.

[SyedAbd110786]

Hi, I am a new contributor and I would like to work on this issue.
I plan to add @SuppressWarnings("serial") to the relevant archetype
files. Can someone confirm this is the right approach?

[kennknowles]

I think this one is obsolete.