title: CosmosDB Graph : "upsert" query pattern
body: <p>I am new to Gremlin query language.
  I have to insert data on a Cosmos DB graph (using Gremlin.Net package), whether the Vertex (or Edge) already exists in the graph or not. If the data exists, I only need to update the properties.
  I wanted to use this kind of pattern:</p>
  
  <pre><code>g.V().hasLabel('event').has('id','1').tryNext().orElseGet {g.addV('event').has('id','1')}
  </code></pre>
  
  <p>But it is not supported by Gremlin.Net / Cosmos DB graph API. Is there a way to make a kind of upsert query in a single query ?</p>
  
  <p>Thanks in advance.</p>