diff --git a/java/org/slub/rosetta/dps/repository/plugin/ValidationCatalogResolver.java b/java/org/slub/rosetta/dps/repository/plugin/ValidationCatalogResolver.java
index e42a5740714ff7be5acca41af706f10bc5e5ad0b..9dfa1e147b012842b06e607923981c7aeb27f67b 100644
--- a/java/org/slub/rosetta/dps/repository/plugin/ValidationCatalogResolver.java
+++ b/java/org/slub/rosetta/dps/repository/plugin/ValidationCatalogResolver.java
@@ -13,18 +13,18 @@ import java.io.InputStream;
 import java.util.List;
 
 class ValidationCatalogResolver implements CatalogResolver {
-    private String[] catalogs;
-    private List<String> errors = null;
+    private final String[] catalogs;
+    private List<String> errors;
     ValidationCatalogResolver(String[] catalogs, List<String> errors) {
         this.catalogs = catalogs;
         this.errors = errors;
     }
     @Override
     public InputSource resolveEntity(String publicId, String systemId) {
-        System.out.println("======");
-        System.out.println("resolveEntity publicId=" + publicId + " systemId=" + systemId);
+        //System.out.println("======");
+        //System.out.println("resolveEntity publicId=" + publicId + " systemId=" + systemId);
         if (catalogs.length == 0) {
-            System.out.println("No catalog given!");
+            //System.out.println("No catalog given!");
             errors.add("No catalog given!");
             return null;
         }
@@ -35,7 +35,7 @@ class ValidationCatalogResolver implements CatalogResolver {
             cr.setCatalogList(catalogs);
             result = cr.resolveEntity(publicId, systemId);
         } catch (IOException | CatalogException | SAXException e) {
-            System.out.println("No mapping found for publicId=" + publicId + ", systemId=" + systemId + ", " + e.getMessage());
+            //System.out.println("No mapping found for publicId=" + publicId + ", systemId=" + systemId + ", " + e.getMessage());
             errors.add("No mapping found for publicId=" + publicId + ", systemId=" + systemId + ", " + e.getMessage());
         }
         return result;
@@ -43,23 +43,23 @@ class ValidationCatalogResolver implements CatalogResolver {
 
     @Override
     public Source resolve(String href, String base) {
-        System.out.println("======");
-        System.out.println("resolve href=" + href + " base=" + base);
+        //System.out.println("======");
+        //System.out.println("resolve href=" + href + " base=" + base);
 
         return null;
     }
 
     @Override
     public InputStream resolveEntity(String publicId, String systemId, String baseUri, String nameSpace) {
-        System.out.println("======");
-        System.out.println("resolveEntity2 publicId=" + publicId + " systemId=" + systemId);
+        //System.out.println("======");
+        //System.out.println("resolveEntity2 publicId=" + publicId + " systemId=" + systemId);
         return null;
     }
 
     @Override
     public LSInput resolveResource(String type, String namespaceURI, String publicId, String systemId, String baseUri) {
-        System.out.println("======");
-        System.out.println("resolveResource publicId=" + publicId + " systemId=" + systemId);
+        //System.out.println("======");
+        //System.out.println("resolveResource publicId=" + publicId + " systemId=" + systemId);
         return null;
     }
 }