dev-java/itext version 5.0.5 is available and its non-existence in portage is blocking #331981. Unfortunately, just renaming the ebuild of 2.1.5 does not work ("package org.bouncycastle.tsp does not exist") so perhaps dev-java/bcprov (or something like that) also needs a bump.
I already added bcprov-tsp package to java-overlay. Please try that.
A lot more is needed than bctsp. itext moved to AGPL-3 and seems to require maven now. Current version: 5.1.3
Bumped to version 5.2.0