How to get default constructor parameter using reflection?

This kind of seemed easy to figure out but now am confused:

scala> class B(i:Int)
defined class B

scala> classOf[B].getDeclaredFields
res12: Array[java.lang.reflect.Field] = Array()

Note this:

scala> class C(i:Int){
     | val j = 3
     | val k = -1
     | }
defined class C

scala> classOf[C].getDeclaredFields
res15: Array[java.lang.reflect.Field] = Array(private final int C.j, private final int C.k)