diff --git a/composer.json b/composer.json
index f3afe122..58cc2c0e 100644
--- a/composer.json
+++ b/composer.json
@@ -7,7 +7,7 @@
         "php": "^8.0",
         "ext-curl": "*",
         "ext-json": "*",
-        "netresearch/jsonmapper": "^3.0|^4.0|^5.0",
+        "netresearch/jsonmapper": "^4.2",
         "monolog/monolog": "^2.0|^3.0"
     },
     "suggest": {
diff --git a/src/Issue/Version.php b/src/Issue/Version.php
index eb3b23a6..30b57ed1 100644
--- a/src/Issue/Version.php
+++ b/src/Issue/Version.php
@@ -11,27 +11,27 @@ class Version implements \JsonSerializable
     public string $id;
 
     // Version name: ex: 4.2.3
-    public ?string $name;
+    public string $name;
 
     // version description: ex; improvement performance
-    public ?string $description;
+    public ?string $description = null;
 
     public bool $archived;
 
     public bool $released;
 
-    public string $releaseDate;
+    public ?string $releaseDate = null;
 
-    public bool $overdue;
+    public bool $overdue = false;
 
-    public ?string $userReleaseDate;
+    public ?string $userReleaseDate = null;
 
     public int $projectId;
 
-    public ?string $startDate;
-    public ?string $userStartDate;
+    public ?string $startDate = null;
+    public ?string $userStartDate = null;
 
-    public function __construct($name = null)
+    public function __construct(string $name)
     {
         $this->name = $name;
     }
diff --git a/src/Version/VersionService.php b/src/Version/VersionService.php
index 17512e6b..fee0ab48 100644
--- a/src/Version/VersionService.php
+++ b/src/Version/VersionService.php
@@ -35,7 +35,7 @@ public function create($version)
 
         return $this->json_mapper->map(
             json_decode($ret),
-            new Version()
+            Version::class
         );
     }
 
@@ -71,7 +71,7 @@ public function get(string $id)
 
         return $this->json_mapper->map(
             json_decode($ret),
-            new Version()
+            Version::class
         );
     }
 
@@ -100,7 +100,7 @@ public function update(Version $version): Version
 
         return $this->json_mapper->map(
             json_decode($ret),
-            new Version()
+            Version::class
         );
     }