Tweaks for new Objective-C API.

webrtc/api/objc/RTCIceServer.h

Index: webrtc/api/objc/RTCIceServer.h
diff --git a/webrtc/api/objc/RTCIceServer.h b/webrtc/api/objc/RTCIceServer.h
index be4e0d7b6e89da90cbbbc38faa53826bd3bc59b6..98fe14fe9362d6433a9a9a304501313eae9681cf 100644
--- a/webrtc/api/objc/RTCIceServer.h
+++ b/webrtc/api/objc/RTCIceServer.h
@@ -15,13 +15,13 @@ NS_ASSUME_NONNULL_BEGIN
 @interface RTCIceServer : NSObject
 
 /** URI(s) for this server represented as NSStrings. */
-@property(nonatomic, copy, readonly) NSArray<NSString *> *urlStrings;
+@property(nonatomic, readonly) NSArray<NSString *> *urlStrings;
 
 /** Username to use if this RTCIceServer object is a TURN server. */
-@property(nonatomic, copy, readonly, nullable) NSString *username;
+@property(nonatomic, readonly, nullable) NSString *username;
 
 /** Credential to use if this RTCIceServer object is a TURN server. */
-@property(nonatomic, copy, readonly, nullable) NSString *credential;
+@property(nonatomic, readonly, nullable) NSString *credential;
 
 - (instancetype)init NS_UNAVAILABLE;