Implemented getObjectNode as well, renamed other function for consistency

CloudObjects/SDK/CloudObject.php

@@ -66,7 +66,7 @@ class CloudObject {
     /**
      * Get the object node encapsulated in this CloudObject.
      */
-    public function getObjectNode() : Node {
+    public function getAsNode() : Node {
         return $this->node;
     }
 
@@ -133,4 +133,20 @@ class CloudObject {
         return $this->retriever->getCloudObject($coid);
     }
 
+
+    /**
+     * Get the value of a property and, if it's a COID, retrieve the corresponding object node.
+     */
+    public function getObjectNode($property) : ?Node {
+        Assert::notNull($this->retriever, "No ObjectRetriever set for CloudObject. Cannot retrieve related object.");
+
+        $coid = $this->getReader()->getFirstValueIRI($this->node, $property);
+
+        if (!($coid instanceof IRI)) {
+            return null;
+        }
+
+        return $this->retriever->getObjectNode($coid);
+    }    
+
 }