Updated some interfaces, made time syncing methods nullable for apis not using it, added optional retry checking, removed private key from api credentials, added better support for api credentials subclasses

CryptoExchange.Net/Authentication/ApiCredentials.cs

@@ -21,20 +21,6 @@ namespace CryptoExchange.Net.Authentication
         /// </summary>
         public SecureString? Secret { get; }
 
-        /// <summary>
-        /// The private key to authenticate requests
-        /// </summary>
-        public PrivateKey? PrivateKey { get; }
-
-        /// <summary>
-        /// Create Api credentials providing a private key for authentication
-        /// </summary>
-        /// <param name="privateKey">The private key used for signing</param>
-        public ApiCredentials(PrivateKey privateKey)
-        {
-            PrivateKey = privateKey;
-        }
-
         /// <summary>
         /// Create Api credentials providing an api key and secret for authentication
         /// </summary>
@@ -69,11 +55,8 @@ namespace CryptoExchange.Net.Authentication
         /// <returns></returns>
         public virtual ApiCredentials Copy()
         {
-            if (PrivateKey == null)
-                // Use .GetString() to create a copy of the SecureString
-                return new ApiCredentials(Key!.GetString(), Secret!.GetString());
-            else
-                return new ApiCredentials(PrivateKey!.Copy());
+            // Use .GetString() to create a copy of the SecureString
+            return new ApiCredentials(Key!.GetString(), Secret!.GetString());
         }
 
         /// <summary>
@@ -123,7 +106,6 @@ namespace CryptoExchange.Net.Authentication
         {
             Key?.Dispose();
             Secret?.Dispose();
-            PrivateKey?.Dispose();
         }
     }
 }