object Test {
  def main(args: Array[String]) {
    val jl = classOf[Foo].getMethod("jl", classOf[Baz[_]])
    jl.getGenericParameterTypes // works fine

    val l = classOf[Foo].getMethod("l", classOf[Baz[_]])
    // By debugger inspection l.signature is (Ltest/Baz<J>;)V
    l.getGenericParameterTypes // throws GenericSignatureFormatError
  }
}

class Baz[T]

class Foo {
  def l(b: Baz[Long]) { }
  def jl(b: Baz[java.lang.Long]) { }
}