title: Couchbase can't MutateIn multiple upserts with null value
body: <p>I have a Couchbase document that I want to mutate multiple properties on in one call. If one of the property values is null, the mutate fails with a message of: </p>
  
  <blockquote>
    <p>KV Error: {Name="EINVAL", Description="Invalid packet", Attributes="internal,invalid-input"}</p>
  </blockquote>
  
  <p>and a status of </p>
  
  <blockquote>
    <p>Couchbase.IO.ResponseStatus.InvalidArguments</p>
  </blockquote>
  
  <p>If I just try to mutate a single property with null, and if none of the property values are null. The mutate will be successful.</p>
  
  <p>Also if I try to mutate multiple properties to null it will fail.</p>
  
  <pre class="lang-cs prettyprint-override"><code>// This works
  var mutatedWorks1 = bucket.MutateIn&lt;dynamic&gt;(doc1.DocId)
      .Upsert("nullProperty", "NotNull")
      .Upsert("name", "MutatedName")
      .Execute();
  
  // This also works
  var mutatedWorks2 = bucket.MutateIn&lt;dynamic&gt;(doc1.DocId)
      .Upsert("nullProperty", null)
      .Execute();
  
  // This doesn't work
  var mutatedNotWork = bucket.MutateIn&lt;dynamic&gt;(doc1.DocId)
      .Upsert("nullProperty", null)
      .Upsert("name", "MutatedName")
      .Execute();      
  
  // This also doesn't work
  var mutatedNotWork = bucket.MutateIn&lt;dynamic&gt;(doc1.DocId)
      .Upsert("nullProperty", null)
      .Upsert("name", null)
      .Execute();   
  </code></pre>
  
  <p>Couchbase client is .Net SDK 2.7.10</p>
  
  <p>How can I mutate multiple properties if one or more of the property values are null?</p>