JSON interpolation and identifier errors

In my IDE settings (Linux IDEA 14.0.2, Scala plugin 1.2.1) I've set json interpolated String prefix to JSON -Language ID. Here's an example of using it:

def example(foos: List[Foo], limit: Int) = {
    |  "size": $
    |  "query": {
    |    "terms": { "foo.id": $
{foos.map(_.id)} }
    |  }

The IDE highlights the usage of interpolated values (of type org.json4s.JValue) saying "JSON standard does not allow identifiers". I would expect that no errors would be shown for interpolated values.