link source is cool

build.gradle

@@ -100,6 +100,7 @@ mixin {
 
 javadoc {
     options.addStringOption('Xwerror', '-quiet') // makes the build fail on travis when there is a javadoc error
+    options.linkSource true
     source += sourceSets.api.allJava
     classpath += sourceSets.api.compileClasspath
 }