in Sources/SparkConnect/Extension.swift [212:223]
func toString() throws -> String {
let startFieldName = try fieldToString(self.startField)
let endFieldName = try fieldToString(self.endField)
let interval = if startFieldName == endFieldName {
"interval \(startFieldName)"
} else if startFieldName < endFieldName {
"interval \(startFieldName) to \(endFieldName)"
} else {
throw SparkConnectError.InvalidTypeException
}
return interval
}