After upgrading to java 19 we started seeing InvalidUseOfMatchersException errors coming from mockito.
trait Foo {
  def bar(a: String, b: Int = 1): Int
}
object Test extends org.mockito.IdiomaticMockito {
  def main(args: Array[String]): Unit = {
    val x = mock[Foo]
    x.bar("a").returns(2)
  }
}
Above code works fine on java 17 but throws on java 19.