title: Add external jar in gradle
body: <p>How can I add an external library in gradle? My <code>build.gradle</code> contains:</p>
  
  <pre class="lang-groovy prettyprint-override"><code>buildscript {
      repositories {
          mavenCentral()
          maven {
              name = "forge"
              url = "http://files.minecraftforge.net/maven"
          }
          maven {
              name = "sonatype"
              url = "https://oss.sonatype.org/content/repositories/snapshots/"
          }
      }
      dependencies {
          classpath 'net.minecraftforge.gradle:ForgeGradle:1.1-SNAPSHOT'
      }
  }
  </code></pre>
  
  <p>My root folder is <code>/FORGE/</code>. I want to add <code>/FORGE/build/libs/spigot.jar</code> as a dependency.</p>