Fixed foundry rewrite.

Change-Id: I790af4052610afad98a31a1376c89caaa66699f8
diff --git a/core/src/main/java/de/ids_mannheim/korap/resource/rewrite/FoundryInject.java b/core/src/main/java/de/ids_mannheim/korap/resource/rewrite/FoundryInject.java
index 948ec50..675522d 100644
--- a/core/src/main/java/de/ids_mannheim/korap/resource/rewrite/FoundryInject.java
+++ b/core/src/main/java/de/ids_mannheim/korap/resource/rewrite/FoundryInject.java
@@ -42,7 +42,7 @@
             mapper = new LayerMapper(config);
             
         if (node.get("@type").equals("koral:span")) {
-            if (!node.at("/wrap").rawNode().isMissingNode()){
+            if (!node.isMissingNode("/wrap")){
                 JsonNode term = rewriteQuery(node.at("/wrap"), config, user);
                 node.replaceAt("/wrap", term, new RewriteIdentifier("koral:term", "replace"));
             }
diff --git a/core/src/main/java/de/ids_mannheim/korap/resource/rewrite/KoralNode.java b/core/src/main/java/de/ids_mannheim/korap/resource/rewrite/KoralNode.java
index 0614f91..70f23bc 100644
--- a/core/src/main/java/de/ids_mannheim/korap/resource/rewrite/KoralNode.java
+++ b/core/src/main/java/de/ids_mannheim/korap/resource/rewrite/KoralNode.java
@@ -265,4 +265,9 @@
         }
 
     }
+
+
+    public boolean isMissingNode (String string) {
+        return this.node.at(string).isMissingNode();
+    }
 }