bring back some imp code that were removed previously and fix some nits

Author: aniruddha2000

pkg/client/sdk.go

@@ -298,7 +298,7 @@ func (c *SdkStackitClient) GetNICsForServer(ctx context.Context, projectID, regi
 }
 
 func (c *SdkStackitClient) ListNICs(ctx context.Context, projectID, region, networkID string) ([]*NIC, error) {
-	res, err := c.iaasClient.ListNics(ctx, projectID, region, networkID).Execute()
+	res, err := c.iaasClient.DefaultAPI.ListNics(ctx, projectID, region, networkID).Execute()
 	if err != nil {
 		return nil, fmt.Errorf("SDK ListServerNICs failed: %w", err)
 	}
@@ -308,15 +308,15 @@ func (c *SdkStackitClient) ListNICs(ctx context.Context, projectID, region, netw
 	}
 
 	nics := make([]*NIC, 0)
-	for _, nic := range *res.Items {
+	for _, nic := range res.Items {
 		nics = append(nics, convertSDKNICtoNIC(&nic))
 	}
 
 	return nics, nil
 }
 
 func (c *SdkStackitClient) DeleteNIC(ctx context.Context, projectID, region, networkID, nicID string) error {
-	err := c.iaasClient.DeleteNic(ctx, projectID, region, networkID, nicID).Execute()
+	err := c.iaasClient.DefaultAPI.DeleteNic(ctx, projectID, region, networkID, nicID).Execute()
 	if err != nil {
 		// Check if error is 404 Not Found - this is OK (idempotent)
 		if isNotFoundError(err) {
@@ -393,3 +393,10 @@ func isNotFoundError(err error) bool {
 	}
 	return false
 }
+
+func getStringValue(s *string) string {
+	if s == nil {
+		return ""
+	}
+	return *s
+}