Added a has() method to CloudObject

CloudObjects/SDK/CloudObject.php

@@ -74,6 +74,13 @@ class CloudObject {
         return $this->node;
     }
 
+    /**
+     * Checks if a property exists on this object.
+     */
+    public function has($property) : bool {
+        return $this->getReader()->hasProperty($this->node, $property);
+    }
+
     /**
      * Get the value of a property as a string.
      * If the property has multiple values, only the first is returned.
@@ -137,7 +144,6 @@ class CloudObject {
         return $this->retriever->getCloudObject($coid);
     }
 
-
     /**
      * Get the value of a property and, if it's a COID, retrieve the corresponding object node.
      */