Scala trait ABI

TestTrait.java

package main;

public interface TestTrait {
    public default int method(int x) {
        return x * 2;
    }
}

TestTrait.scala

package main

trait TestTrait {
    def method(x: Int): Unit = {
        x * 2
    }
}

TestTrait_java.txt

// Generated by running 'javap -c TestTrait'

Compiled from "TestTrait.java"
public interface main.TestTrait {
  public int method(int);
    Code:
       0: iload_1
       1: iconst_2
       2: imul
       3: ireturn
}

TestTrait_scala.txt

// Generated by running 'javap -c TestTrait'

Compiled from "TestTrait.scala"
public interface main.TestTrait {
  public static void method$(main.TestTrait, int);
    Code:
       0: aload_0
       1: iload_1
       2: invokespecial #16                 // InterfaceMethod method:(I)V
       5: return

  public void method(int);
    Code:
       0: iload_1
       1: iconst_2
       2: imul
       3: pop
       4: return

  public static void $init$(main.TestTrait);
    Code:
       0: return
}