False positive-ish: no way to suppress warnings on imports

[marconilanna]

This relates to wartremover/wartremover#410

Given that there is no way to annotate imports, maybe OldTime should not be warning about them, but only about usage sites.

import java.util.Date // wartremover error here. how to whitelist it?

@SuppressWarnings(Array(Warts.OldTime))
class X {
  def y = legacyJavaApi.z(new Date)
}

[amanjpro]

That should be easy, will try to find time to address it.

[pmpfr]

I only notice this now it's no longer a problem, but a workaround would probably be to move the import in to more local scope inside an annotation.