api: pointer conversion functions should return nil for nil input

Signed-off-by: Dimitrios Karagiannis <[email protected]>

megaport/api/helpers.go

@@ -1,21 +1,33 @@
 package api
 
 func String(v interface{}) *string {
+	if v == nil {
+		return nil
+	}
 	r := v.(string)
 	return &r
 }
 
 func Uint64(v interface{}) *uint64 {
+	if v == nil {
+		return nil
+	}
 	r := v.(uint64)
 	return &r
 }
 
 func Uint64FromInt(v interface{}) *uint64 {
+	if v == nil {
+		return nil
+	}
 	r := uint64(v.(int))
 	return &r
 }
 
 func Bool(v interface{}) *bool {
+	if v == nil {
+		return nil
+	}
 	r := v.(bool)
 	return &r
 }