SLIDER-1243 Enable XML validation in ConfigHelper
diff --git a/slider-core/src/main/java/org/apache/slider/common/tools/ConfigHelper.java b/slider-core/src/main/java/org/apache/slider/common/tools/ConfigHelper.java
index 9db241d..a1dd6f4 100644
--- a/slider-core/src/main/java/org/apache/slider/common/tools/ConfigHelper.java
+++ b/slider-core/src/main/java/org/apache/slider/common/tools/ConfigHelper.java
@@ -308,6 +308,7 @@
     //allow includes in the xml file
     docBuilderFactory.setNamespaceAware(true);
     docBuilderFactory.setXIncludeAware(true);
+    docBuilderFactory.setValidating(true);
     DocumentBuilder builder = docBuilderFactory.newDocumentBuilder();
     return builder.parse(in);
   }