Use Intellij project configuration for Gradle

I have just started using Gradle so I apologize if I’m missing something very obvious.

I would like to be able to automatically compile my Java project with Travis CI.

Travis CI requires some sort of build tool to be set up. I have chosen Gradle as it seemed to be somewhat popular. As my project is already correctly set up in Intellij I wanted to just migrate the settings such as the local jar dependencies and the artifact settings to Gradle. Unfortunately I was not able to get this to work at all.

I have tried this suggestion as well as completely setting up an empty Gradle project with Intellij and manually set up the settings again in Intellij but it seems that the Intellij settings are completely separated from the build.gradle file even with the Gradle plugin.

Is a migration from intellij project settings not possible to Gradle?
Are there other options than setting up a build.gradle file by hand? - (I have spent the entire day trying to figure out how to set this up correctly but already failed with the simple task of including local jar dependencies to into the generated jar file.)
Or is there a much simpler solution to my initial goal to use Travis CI?

(Here the repo if needed)

Thanks in advance!