LookupInResult.contentAs(i, Boolean.class) throws PathNotFound for `exists` spec

The following code throws PathNotFoundException. Expected result is printing "false".

collection.upsert("foo", mapOf("magicWord", "xyzzy"));

LookupInResult r = collection.lookupIn("foo", listOf(

  LookupInSpec.exists("non-existent-path"))

);

System.out.println(r.contentAs(0, Boolean.class));

First, investigate whether SDK 3 or supported versions of Couchbase Server have ever behaved differently. If this is not a regression, then leave it unchanged so we don't break existing code, and make sure the docs recommend getting the result using LookupInResult.exists instead of contentAs.