Improve comments for FillParameters

builder/azure/arm/builder.go

@@ -57,7 +57,7 @@ func (b *Builder) Run(ctx context.Context, ui packer.Ui, hook packer.Hook) (pack
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()
 
-	// FillParameters function will set the authType from supplied parameters set the subscription and tenant id.
+	// FillParameters function captures authType and sets defaults.
 	err := b.config.ClientConfig.FillParameters()
 	if err != nil {
 		return nil, err

builder/azure/common/client/config.go

@@ -254,6 +254,8 @@ func (c Config) GetServicePrincipalTokens(
 	return servicePrincipalToken, servicePrincipalTokenVault, nil
 }
 
+// FillParameters capture the user intent from the supplied parameter set in authType, retrieves the TenantID and CloudEnvironment if not specified.
+// The SubscriptionID is also retrieved in case MSI auth is requested.
 func (c *Config) FillParameters() error {
 	if c.authType == "" {
 		if c.useDeviceLogin() {