As I warned at https://cwiki.apache.org/confluence/display/OFBIZ/About+OWASP+Dependency+Check it's currently difficult to separate the OFBiz jars from other jars in the .gradle\caches contains which may contain jars unrelated to OFBiz. Notably Eclipse jars if you use the Gradle Eclipse task and more if you use Gradle for other reasons than OFBiz.
I did not find yet a way to avoid to have all external jars in .gradle\caches and I wonder if it's even possible. What I would like to have is the external jars mandatory for OFBiz to work in an isolated place. For instance a sub folder of the main Gradle build folder. I picked $buildDir/externalJars.