I wrote metadata for GPL RxDroid, problem is I am not the original author and I don't develop android apps yet so I was unable to test whether it would compile successfully.
When I used Gradle 3.2 from Android studio on my machine and did
fdroid build -v -l at.jclehner.rxdroid it resulted in
* What went wrong: A problem occurred evaluating root project 'RxDroid'. > Failed to apply plugin [id 'com.android.application'] > Gradle version 2.10 is required. Current version is 3.2. If using the gradle wrapper, try editing the distributionUrl in /temp/fdroiddata/build/at.jclehner.rxdroid/gradle/wrapper/gradle-wrapper.properties to gradle-2.10-all.zip
I would like to see RxDroid in F-Droid. Thanks!