[FIX] Validation Module: Allow document nodes as input.

Author: ChristianGruen

basex-core/src/main/java/org/basex/query/func/validate/ValidateXsd.java

@@ -94,8 +94,8 @@ void process(final ErrorHandler handler) throws IOException, SAXException, Query
 
         final Validator v = s.newValidator();
         v.setErrorHandler(handler);
-        final String url = in.url();
-        v.validate(url.isEmpty() ? new StreamSource(in.inputStream()) : new StreamSource(url));
+        v.validate(in instanceof IOContent || in instanceof IOStream ?
+            new StreamSource(in.inputStream()) : new StreamSource(in.url()));
       }
     });
   }