predicate doesn't work on modified

[mocha-coffee-jp]

Step 1: Describe your environment

• Xcode version:10.1
• Pring version: 0.16.1

Step 3: Describe the problem

Steps to reproduce:

1. Create User and Save

let user: User = User()
user.name = "hoge"
user.save()

2. Create Option and set predicate.

let option = Options()
option.predicate = NSPredicate(format: "name == %@", "moge")

3. Create DataSource

  let dataSource = UserInfo.dataSource(options: option)
     .on({ [weak self] (snapshot, changes) in
            switch changes {
                case .initial:
                    ()
                case .update(let deletions, let insertions, let modifications):
                    ()
                case .error(let error):
                    print(error)
                }
      }).listen()

4. Update UserName
   Update User.name "hoge" to "moge" at FireStore

5. now is user.name = "moge", but never call changes or add event.

Relevant Code:

DataSource.swift - line 305

func _operate() {
   case .modified: 
      guard self.documents.contains(where: { return $0.id == id}) else {
         return
      }
}

Should consider about currently not contains items?
ここでfilterd条件が外れる変更だった場合も考慮するべき？