squash: Note that empty trait set is valid

Signed-off-by: David Feltell <david.feltell@foundry.com>

examples/querying_entity_traits.ipynb

@@ -346,6 +346,46 @@
    },
    "id": "dbb66de3947d7b24"
   },
+  {
+   "cell_type": "markdown",
+   "source": [
+    "## An empty trait set is a valid response\n",
+    "\n",
+    "BAL has no restrictions on publishing to new entity references, so what happens if we try to get the trait set for one?"
+   ],
+   "metadata": {
+    "collapsed": false
+   },
+   "id": "1bfdacf358dad9fa"
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "outputs": [],
+   "source": [
+    "new_entity_ref = manager.createEntityReference(\"bal:///some/new/ref\")\n",
+    "\n",
+    "entity_trait_set = manager.entityTraits(new_entity_ref, EntityTraitAccess.kWrite, context)\n",
+    "\n",
+    "helpers.display_result(entity_trait_set)"
+   ],
+   "metadata": {
+    "collapsed": false
+   },
+   "id": "c771cf01dc76f671"
+  },
+  {
+   "cell_type": "markdown",
+   "source": [
+    "...an empty trait set is returned.\n",
+    "\n",
+    "If the manager does not know the trait set, or it's not applicable, the returned trait set may be empty. For example, as illustrated here, the entity reference may point to a new entity with no type constraints. "
+   ],
+   "metadata": {
+    "collapsed": false
+   },
+   "id": "2985087ccc829642"
+  },
   {
    "cell_type": "markdown",
    "source": [