Index: C:/src/jackrabbit/trunk/jackrabbit/src/main/java/org/apache/jackrabbit/core/nodetype/NodeTypeDef.java
===================================================================
--- C:/src/jackrabbit/trunk/jackrabbit/src/main/java/org/apache/jackrabbit/core/nodetype/NodeTypeDef.java	(revision 418367)
+++ C:/src/jackrabbit/trunk/jackrabbit/src/main/java/org/apache/jackrabbit/core/nodetype/NodeTypeDef.java	(working copy)
@@ -69,7 +69,7 @@
         if (dependencies == null) {
             dependencies = new HashSet();
             // supertypes
-            dependencies.addAll(supertypes);
+            dependencies.addAll(Arrays.asList(getSupertypes()));
             // child node definitions
             for (Iterator iter = nodeDefs.iterator(); iter.hasNext();) {
                 NodeDef nd = (NodeDef) iter.next();
@@ -192,17 +192,21 @@
     }
 
     /**
-     * Returns an array containing the names of the supertypes or
-     * <code>null</code> if not set.
+     * Returns an array containing the names of the supertypes. If no
+     * supertypes have been set, then <code>nt:base<code> or an empty
+     * array is returned depending on whether type defined type is a
+     * mixin type or <code>nt:base</code> itself.
      *
-     * @return an array listing the names of the supertypes or
-     *         <code>null</code> if not set.
+     * @return an array listing the names of the supertypes (if any)
      */
     public QName[] getSupertypes() {
-        if (supertypes.isEmpty()) {
+        if (!supertypes.isEmpty()) {
+            return (QName[]) supertypes.toArray(new QName[supertypes.size()]);
+        } else if (isMixin() || QName.NT_BASE.equals(getName())) {
             return QName.EMPTY_ARRAY;
+        } else {
+            return new QName[] { QName.NT_BASE };
         }
-        return (QName[]) supertypes.toArray(new QName[supertypes.size()]);
     }
 
     /**
@@ -282,7 +286,7 @@
             NodeTypeDef other = (NodeTypeDef) obj;
             return (name == null ? other.name == null : name.equals(other.name))
                     && (primaryItemName == null ? other.primaryItemName == null : primaryItemName.equals(other.primaryItemName))
-                    && supertypes.equals(other.supertypes)
+                    && equals(getSupertypes(), other.getSupertypes())
                     && mixin == other.mixin
                     && orderableChildNodes == other.orderableChildNodes
                     && propDefs.equals(other.propDefs)
@@ -291,6 +295,12 @@
         return false;
     }
 
+    private static boolean equals(QName[] a, QName[] b) {
+        Arrays.sort(a);
+        Arrays.sort(b);
+        return Arrays.equals(a, b);
+    }
+
     /**
      * Returns zero to satisfy the Object equals/hashCode contract.
      * This class is mutable and not meant to be used as a hash key.