code: public Collection<String> getPropertyNames() throws RepositoryException
     {
        // List <String> propnames = new ArrayList<String>();
        PropertyIterator iter = node.getProperties();
        ArrayList<String> props = new ArrayList<String>();
        while (iter.hasNext())
        {
           String name = iter.nextProperty().getName();
           if (!"jcr:primaryType".equals(name) && !"jcr:mixinTypes".equals(name))
              props.add(name);
        }
        props.addAll(content.getPropertyNames());
        return props;
     }
docs: /*
  (non-Javadoc)
  @see org.exoplatform.services.jcr.ext.resource.NodeRepresentation#getPropertyNames()