code: private void printNamespaces(NodeTypeData nodeTypeData, OutputStreamWriter out) throws RepositoryException,
        IOException
     {
  
        /**
         * Using set to store all prefixes found in node types to avoid
         * duplication
         */
        Set<String> namespaces = new HashSet<String>();
        /** Scanning nodeType definition for used namespaces */
        printNameNamespace(nodeTypeData.getName(), namespaces);
        printNameNamespace(nodeTypeData.getPrimaryItemName(), namespaces);
        if (nodeTypeData.getDeclaredSupertypeNames() != null)
        {
           for (InternalQName reqType : nodeTypeData.getDeclaredSupertypeNames())
           {
              printNameNamespace(reqType, namespaces);
           }
        }
        /** Scanning property definitions for used namespaces */
        if (nodeTypeData.getDeclaredPropertyDefinitions() != null)
        {
           for (PropertyDefinitionData property : nodeTypeData.getDeclaredPropertyDefinitions())
           {
              printNameNamespace(property.getName(), namespaces);
           }
        }
        /** Scanning child definitions for used namespaces */
        if (nodeTypeData.getDeclaredChildNodeDefinitions() != null)
        {
           for (NodeDefinitionData child : nodeTypeData.getDeclaredChildNodeDefinitions())
           {
              printNameNamespace(child.getName(), namespaces);
              printNameNamespace(child.getDefaultPrimaryType(), namespaces);
              if (child.getRequiredPrimaryTypes() != null)
              {
                 for (InternalQName reqType : child.getRequiredPrimaryTypes())
                 {
                    printNameNamespace(reqType, namespaces);
                 }
              }
           }
        }
        for (String prefix : namespaces)
        {
           String uri = namespaceRegistry.getURI(prefix);
           out.write("<" + prefix + "='" + uri + "'>\r\n");
        }
     }
docs: Print namespaces to stream
  
  @param nodeTypeData
  @param out
  @throws RepositoryException
  @throws IOException