Index: oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/nodetype/PropertyDefinitionImpl.java
===================================================================
--- oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/nodetype/PropertyDefinitionImpl.java	(revision 1616683)
+++ oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/nodetype/PropertyDefinitionImpl.java	(working copy)
@@ -90,7 +90,11 @@
     @Override
     public String[] getValueConstraints() {
         // TODO: namespace mapping?
-        return getStrings(JcrConstants.JCR_VALUECONSTRAINTS);
+        String[] valConstraints = getStrings(JcrConstants.JCR_VALUECONSTRAINTS);
+        if (valConstraints != null) {
+            return valConstraints;
+        }
+        return new String[0];
     }
 
     @Override