AbstractMethodError when inheriting trait from java abstract class and referencing val from the trait

This is the exact same bug as in Scala 2: https://github.com/scala/bug/issues/12456

trait ScalaTrait {
  def foo1: String
  def foo2: String = "default foo value 2"

  val val1: String
  val val2: String = "default val value 2"
}

public abstract class JavaAbstractClass implements ScalaTrait {
    public String javaFoo1() { return foo1(); }
    public String javaFoo2() { return foo2(); }

    public String javaVal1() { return val1(); }
    public String javaVal2() { return val2(); }
}

import scala.util.Try

object ScalaClass extends JavaAbstractClass {
  override def foo1: String = "implemented foo in scala 1"
  override val val1: String = "implemented val in scala 1"

  def main(args: Array[String]): Unit = {
    println(Try(javaFoo1()))
    println(Try(javaFoo2()))

    println(Try(javaVal1()))
    println(Try(javaVal2()))
  }
}

problem

The program compiles fine, but an exception is thrown at runtime:

Success(implemented foo in scala 1)
Success(default foo value 2)
Success(implemented val in scala 1)
Exception in thread "main" java.lang.AbstractMethodError: Method ScalaClass$.val2()Ljava/lang/String; is abstract
	at ScalaClass$.val2(ScalaClass.scala)
	at JavaAbstractClass.javaVal2(JavaAbstractClass.java:6)
	at ScalaClass$.$anonfun$main$4(ScalaClass.scala:12)
	at scala.util.Try$.apply(Try.scala:210)
	at ScalaClass$.main(ScalaClass.scala:12)
	at ScalaClass.main(ScalaClass.scala)

[smarter]

and not create a setter method at all?

This doesn’t sound like a binary compatible change, so not something we can do in scala 3.

[anatoliykmetyuk]

This issue was picked for the Issue Spree 15 of May 3rd which takes place a week from now. @gagandeepkalra and @ghostbuster91 will be working on it. If you have any insight into the issue or guidance on how to fix it, please leave it here.