 }
 
 // CollectionDifference<ChangeElement> is conditionally bridged to NSOrderedCollectionDifference
-@available(iOS 9999, macOS 9999, tvOS 9999, watchOS 9999, *) // FIXME(availability-5.1)
+@available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
 extension CollectionDifference : _ObjectiveCBridgeable {
   @_semantics("convertToObjectiveC")
   public func _bridgeToObjectiveC() -> NSOrderedCollectionDifference {

  
  @_effects(readonly)
  public static func _unconditionallyBridgeFromObjectiveC(_ s: NSOrderedCollectionDifference?) -> CollectionDifference {
    return _formDifference(from: s!) { $0 as! Change }!
  }
}

@_exported import Foundation // Clang module

// CollectionDifference<ChangeElement>.Change is conditionally bridged to NSOrderedCollectionChange
@available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *)
extension CollectionDifference.Change : _ObjectiveCBridgeable {
  @_semantics("convertToObjectiveC")
  public func _bridgeToObjectiveC() -> NSOrderedCollectionChange {
