We'd like a method exposed in the stitch support library that returns a list of fields in a given query.

i.e. given

{
  $and: [
    { $or: [ { field1: { $lt : 10 }, { field2: { $in: [50, 30] } ] },
    { $or: [ { field3: "abc" }, { field2: { $gt : 5 } ] }
  ]
}

it would return

[field1, field2, field3]