How to load Java classes from *.jar

[kmaci3k]

I have following Jarfile:
repository 'file:///Users/$USER/.m2/repository'
local_repo 'lib/java'
jar 'com.company.app:my-artifact:0.0.1-SNAPSHOT'

I run lockjar lock and all dependencies are downloaded to lib/java. When I build gem, all .jar dependencies are in lib/java.

How should I load .jars so that any class would be available through java_import ?