How to add external libraries?

[Frontear]

I've already modified the build.gradle to compile org.reflections, which can be found here. The problem is while the dev environment can build it, it will not work after using `gradle build`. I've tried running `gradle buildDependents` as well, and nothing will solve the issue. How can I correctly compile an external library into my mod?

 

Edit: What I mean to say is that the official Minecraft Client will not run the mod, throwing a NoClassDefFound, meaning org.reflections isn't compiling with my mod. How can I make it so?

Edited November 20, 2018 by Frontear

[Frontear]

I have done that, correct? Inside the build.gradle, in the `dependencies` area, I've added 

compile group: 'org.reflections', name: 'reflections', version: '0.9.11'

It works in the dev env, but doesn't compile alongside the Java Jar.

[Frontear]

The documentation isn't clear about how to implement them. It's only telling me the format, the maven support, and some other stuff about modifying the Manifest INF. How exactly am I supposed to accept this? Am I supposed to modify files outside of the build.gradle?