diff --git a/src/Issue/IssueField.php b/src/Issue/IssueField.php
index 8f96bca..3a74424 100644
--- a/src/Issue/IssueField.php
+++ b/src/Issue/IssueField.php
@@ -114,7 +114,7 @@ public function __construct($updateIssue = false)
     public function jsonSerialize(): mixed
     {
         $vars = array_filter(get_object_vars($this), function ($var) {
-            return !is_null($var);
+            return !empty($var);
         });
 
         // if assignee property has empty value then remove it.