Don't render null as default value as properties are null by default

Author: wol-soft

src/Model/Property/Property.php

@@ -242,9 +242,9 @@ public function setDefaultValue($defaultValue): PropertyInterface
     /**
      * @inheritdoc
      */
-    public function getDefaultValue()
+    public function getDefaultValue(): ?string
     {
-        return var_export($this->defaultValue, true);
+        return $this->defaultValue !== null ? var_export($this->defaultValue, true) : null;
     }
 
     /**

src/Model/Property/PropertyInterface.php

@@ -159,9 +159,9 @@ public function setInternal(bool $isPropertyInternal): PropertyInterface;
     public function setDefaultValue($defaultValue): PropertyInterface;
 
     /**
-     * @return mixed
+     * @return string|null
      */
-    public function getDefaultValue();
+    public function getDefaultValue(): ?string;
 
     /**
      * @return bool

src/Model/Property/PropertyProxy.php

@@ -205,7 +205,7 @@ public function setDefaultValue($defaultValue): PropertyInterface
     /**
      * @inheritdoc
      */
-    public function getDefaultValue()
+    public function getDefaultValue(): ?string
     {
         return $this->getProperty()->getDefaultValue();
     }