Work around apparent Checkstyle bug re. JavaDoc in package-info.java

Work around apparent Checkstyle bug re. JavaDoc in package-info.java

We have earlier agreed to, and aligned our Checkstyle rules accordingly,
not enforce JavaDoc presence, just validate its content if it's present.
However, we are still enforcing every package-info.java (of which we
have almost none..) to have a JavaDoc.

While experimenting with plastering package-info.java into EVERY package
everywhere (to have an annotation @NonNullByDefault package in it..),
I don't want to put in bogus empty JavaDoc into every package just to
satisfy Checkstyle, that would be ridiculous.

Related to https://github.com/checkstyle/checkstyle/issues/3416

Change-Id: I397763f9e09bc7db009ade5da1a5b35bdc518169
Signed-off-by: Michael Vorburger <vorburger@redhat.com>