possible bug around transitive dependencies

Possible bug around transitive dependencies or my misunderstanding of gradle.

Gradle doesn't seem to download commons-collections:commons-collections:jar:3.1 which is a transitive dependency of velocity 1.5

Attached zip contains tiny project that has pom.xml and build.gradle (both are essentially the same). 'mvn test' builds fine (amazingly...) but 'gradle test' fails. One of the tests fails because commons-collections is not on the classpath. It seems commons-collections should be on the classpath because it is a transitive dependency of velocity.