Fix `mvn clean verify` build (including building PlantUML from sources)
Fix `mvn clean verify` build (including building PlantUML from sources)

Signed-off-by: Sjoerd Talsma <1dafb4c4a7acdc6e1eca32ff35fda03e0e9cd976@talsma-ict.nl>

talsma-ict/umldoclet,talsma-ict/umldoclet