Bug#929685: another fix

[Bastian Blank]

Hi

To fix this cycle, which makes any package dependency on
default-jre-headless unstable, I propose to change the dependency in
ca-certificates-java to just specify openjdk-11-jre-headless, without
any default-jre-headless alternative.

Yes, this will cause the default java version to be installed, but this
seems way better then all the alternatives.

Yes, this does not fix the cycle between java and ca-certificates-java,
but at least it breaks less.

Regards,
Bastian

-- 
	"Beauty is transitory."
	"Beauty survives."
		-- Spock and Kirk, "That Which Survives", stardate unknown