Defs.gmk:347:TESTNG_LICENSE := $(call FullPath,$(JUNIT_LICENSE))

jtreg's Makefile is trying to FullPath-ify TESTNG_LICENSE but it is using the wrong variable; copy paste error from

Defs.gmk:316:JUNIT_LICENSE := $(call FullPath,$(JUNIT_LICENSE))

which probably results in using the wrong license file.

There should probably also be a check for when neither TESTNG_HOME nor TESTNG_LICENSE are defined; then fail early.