Add default implementations for three default protocol conformances in the URLSessionDelegate family

Implementing these callbacks without calling the completion handler causes hangs in cases where these methods are called. Add reasonable default behaviors for all of them, to prevent this.

This issue has been in place for at least 8 years for one of these callbacks.

Author: jakepetroules

Sources/FoundationNetworking/URLSession/URLSessionDelegate.swift

@@ -76,7 +76,9 @@ public protocol URLSessionDelegate : NSObjectProtocol, Sendable {
 
 extension URLSessionDelegate {
     public func urlSession(_ session: URLSession, didBecomeInvalidWithError error: Error?) { }
-    public func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @Sendable @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) { }
+    public func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @Sendable @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
+        completionHandler(.performDefaultHandling, nil)
+    }
 }
 
 /* If an application has received an
@@ -244,15 +246,27 @@ public protocol URLSessionDataDelegate : URLSessionTaskDelegate {
 
 extension URLSessionDataDelegate {
 
-    public func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive response: URLResponse, completionHandler: @Sendable @escaping (URLSession.ResponseDisposition) -> Void) { }
+    public func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive response: URLResponse, completionHandler: @Sendable @escaping (URLSession.ResponseDisposition) -> Void) {
+        if self === dataTask.delegate, let sessionDelegate = session.delegate as? URLSessionDataDelegate, self !== sessionDelegate {
+            sessionDelegate.urlSession(session, dataTask: dataTask, didReceive: response, completionHandler: completionHandler)
+        } else {
+            completionHandler(.allow)
+        }
+    }
 
     public func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didBecome downloadTask: URLSessionDownloadTask) { }
 
     public func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didBecome streamTask: URLSessionStreamTask) { }
 
     public func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) { }
 
-    public func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, willCacheResponse proposedResponse: CachedURLResponse, completionHandler: @Sendable @escaping (CachedURLResponse?) -> Void) { }
+    public func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, willCacheResponse proposedResponse: CachedURLResponse, completionHandler: @Sendable @escaping (CachedURLResponse?) -> Void) {
+        if self === dataTask.delegate, let sessionDelegate = session.delegate as? URLSessionDataDelegate, self !== sessionDelegate {
+            sessionDelegate.urlSession(session, dataTask: dataTask, willCacheResponse: proposedResponse, completionHandler: completionHandler)
+        } else {
+            completionHandler(proposedResponse)
+        }
+    }
 }
 
 /*