Merge pull request #8 from mongodb-developer/fix/quick-fix

added index name to console log.

Author: ricardohsmello

java/105_aggregation_pipeline_explain.ipynb

@@ -171,14 +171,21 @@
     "    List.of(match(filter))\n",
     ").explain(ExplainVerbosity.EXECUTION_STATS);\n",
     "\n",
+    "var winningPlan = explainResult\n",
+    "    .get(\"queryPlanner\", Document.class)\n",
+    "    .get(\"winningPlan\", Document.class);\n",
+    "\n",
+    "var inputStage = winningPlan.get(\"inputStage\", Document.class);\n",
+    "var usesIndex = winningPlan.toJson().contains(\"IXSCAN\");\n",
+    "\n",
     "System.out.println(\"Execution time (ms): \" +\n",
     "    explainResult.get(\"executionStats\", Document.class).get(\"executionTimeMillis\"));\n",
     "\n",
-    "System.out.println(\"Index usage: \" +\n",
-    "    explainResult.get(\"queryPlanner\", Document.class)\n",
-    "        .get(\"winningPlan\", Document.class)\n",
-    "        .toJson()\n",
-    "        .contains(\"IXSCAN\"));"
+    "System.out.println(\"Index usage: \" + usesIndex);\n",
+    "\n",
+    "if (inputStage != null && inputStage.getString(\"indexName\") != null) {\n",
+    "    System.out.println(\"Index name: \" + inputStage.getString(\"indexName\"));\n",
+    "}"
    ]
   },
   {