WELD-2464: Prevent NPE in ProtectionDomainCache

[Azquelt]

Prevent NullPointerException in ProtectionDomainCache if
ProtectionDomain.getPermissions() returns null.

[WeldJenkins]

Can one of the admins verify this patch?

[WeldJenkins]

Can one of the admins verify this patch?

[WeldJenkins]

Can one of the admins verify this patch?

[mkouba]

test this please

[Azquelt]

@mkouba You asked me to test this but then merged the PR. Did you want me to open a new PR to add a unit test?

It should be possible to unit test except that getProtectionDomainForProxy is a package-scoped method so the unit test would have to be in the same package or use reflection to call the method and I couldn't see any existing unit tests which do that.

I did test that the change fixes the issue we were seeing in OpenLiberty before submitting it.

[mkouba]

@Azquelt test this please is a phrase that triggers our CI builds (see also https://wiki.jenkins.io/display/JENKINS/GitHub+pull+request+builder+plugin ;-). I don't think a test is needed.

[Azquelt]

Got it, thanks for clearing up my confusion 😃