Created attachment 247339 [details]
Test code that reads JSON from a file and launches the two queries in question

Trying to get the grandchildren in the JSON code below using the selector $['test-root'][*][*] I got unexpected results:

{
  "test-root": {
    "first-child-object":[
      {"grandchild": 1},
      {"grandchild": 2}
    ],
    "second-child-object":[
      {"grandchild": 3}
    ]
  }
}

That selector only returned one element. Nonetheless, the use of the selector $['test-root']['*'][*] returns the three grandchildren objects as expected.

I've tried the selector $['test-root'][*][*] with another JSONPath implementation (in particular the PHP implementation via [1]) and both expressions seem to be accepted and equivalent.

[1] http://jsonpath.curiousconcept.com/