Copy UP-TO-DATE seems to be missing expected behavior

Using Gradle 2.6, the following task is marked as UP-TO-DATE. The env variable is defined, the destination directory exists but it DOES NOT have any of the files in the list. When I run this task, it claims it is UP-TO-DATE. This does not seem like correct behavior to me.

task installDeps(type: Copy) {
    onlyIf { System.env.KARAF_HOME }
    into "$System.env.KARAF_HOME/deploy"
    from configurations.runtime.files

Are there any dependencies in the ‘runtime’ configuration? In any case you should reference runtime.files as it causes eager resolution of the configuration. Instead you should pass the configuration itself as an input to the task.

from configurations.runtime