Use default options for Azure clients. ConfigurationClient doesn't accept null. (#209)

Author: StephenMolloy

src/Azure/AzureKeyVaultConfigBuilder.cs

@@ -169,7 +169,7 @@ public override string GetValue(string key)
         /// Gets a <see cref="SecretClientOptions"/> to initialize the Key Vault SecretClient with. This defaults to <see cref="null"/>.
         /// </summary>
         /// <returns>A token credential.</returns>
-        protected virtual SecretClientOptions GetSecretClientOptions() => null;
+        protected virtual SecretClientOptions GetSecretClientOptions() => new SecretClientOptions();
 
 
 

src/AzureAppConfig/AzureAppConfigurationBuilder.cs

@@ -230,7 +230,7 @@ public override ICollection<KeyValuePair<string, string>> GetAllValues(string pr
         /// Gets a <see cref="ConfigurationClientOptions"/> to initialize the Key Vault SecretClient with. This defaults to <see cref="null"/>.
         /// </summary>
         /// <returns>A token credential.</returns>
-        protected virtual ConfigurationClientOptions GetConfigurationClientOptions() => null;
+        protected virtual ConfigurationClientOptions GetConfigurationClientOptions() => new ConfigurationClientOptions();
 
         private async Task<string> GetValueAsync(string key)
         {