Correct dependency for package needing Java 6?

[Jan Niehusmann <jan@gondor.com>]

Hi,

I'm trying to make a java package build on all debian architectures. As
the source code needs java 6 to compile, it fails on some architectures
when just depending on default-jdk. These are kfreebsd-* and sparc, where
default-jdk installs gcj instead of openjdk.

Depending on openjdk-6-jdk or openjdk-7-jdk would probably fix that
issue. (jdk 6 would suffice, but as it's already quite old and missing
from jessie, depending on openjdk-7-jdk would be better, I guess)

Therefore, I'd like to build-depend on openjdk-7-jdk | java-6-sdk.
But debian java policy states "Packages must be built with default-jdk".

I'd guess that where policy conflicts with reality, reality wins. But
still, as I'm not experienced in java packaging, I'd like to hear your
opinion. Are there better alternatives?

Regards,
Jan