Reactive Streams Publisher<File>

We desire a new Reactive Streams Publisher component. This Publisher shall publish Files collected from a source directory. The Publisher shall publish each File only once in its life time. It shall publish Files already present at the beginning of its life time, and it shall publish Files which appeared during its life time. The Publisher shall not "remember" Files between life times. In case the source directory has multiple Files, there is no requirement on the order in which the Files are published. The component shall be materialized in Java 8. We require the component to pass all tests applicable of Reactive Streams Java TCK. This implies the use of TestNG instead of JUnit. We require delivery in the form of a Gradle project with source and tests. There is strangeness between Gradle and TestNG; we are willing to help with this.