merging cases in between values and types

[Remi Forax]

Hi all,
the current spec support merging/fallthrough cases only when there is a case null,
like
  case null, case Integer i -> // i can use 'i' here
  
First, i'm not sure it's clearly written in the spec, i was not able to pinpoint the rule allowing it.
Then i wonder if this special behavior is special because null is special or if it should work with any values of the type of the type pattern,
i.e. it works because null is a possible value of Integer, in that case, it should also work with any other values like 42

  case 42, case Integer i ->  // i can use 'i' here

So is null a special value or does this rule also work with any values.

regards,
Rémi