Issue: Gradle application plugin using Kotlin is not compiling Java files. Steps: 1. Create gradle application gradle init Select type of project to generate:   1: basic   2: application   3: library   4: Gradle plugin Enter selection (default: basic) [1..4] 2 Select implementation language:   1: C++   2: Groovy   3: Java   4: Kotlin   5: Swift Enter selection (default: Java) [1..5] 4 Select build script DSL:   1: Groovy   2: Kotlin Enter selection (default: Kotlin) [1..2] 2 2. Add SomeJavaClass.java file beside App.kt file class SomeJavaClass{     public void m(){         System.out.println("x");     } } 3. Try to access SomeJavaClass in App.kt main method     SomeJavaClass().m() Excepted Output: Should be able to run Actual Output: no compile issues but crash because of NoClassDefFoundError

It's probably would be better to report issue on Gradle issue tracker