Scala String unique and distinct characters

Scala problem: define in BDD style

When Filter string unique characters 
Then Sort by alphabet


TODO-01: When Filter string unique characters 
Use the distinct method to find the distinct/unique characters in a String:

"hello world".toSeq.distinct.unwrap  // expected "helo wrd"
"bbbaaaccc".toSeq.distinct.unwrap // expected "bac"

*Note: method distinct in class StringOps is deprecated (since 2.13.0): Use `s.toSeq.distinct.unwrap` instead of `s.distinct`

TODO-02: Then Sort by alphabet

"bac".toList.sorted.mkString // expected "abc"