title: dynamodb.put().promise() not returning the put object
body: <p>I am trying to make use of the async/await functionality with regard to aws and dynamo db. Below is an example of how to put an object pre asyn await, as you can see in the callback you have access to data which contains the put object. However in the second block of code which uses async and promise the result is an empty object, any thoughts?</p>
  
  <p><a href="https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GettingStarted.NodeJs.03.html" rel="noreferrer">https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/GettingStarted.NodeJs.03.html</a></p>
  
  <p><strong>Non Promise Version</strong></p>
  
  <pre><code>var docClient = new AWS.DynamoDB.DocumentClient();
  
  var table = "Movies";
  
  var year = 2015;
  var title = "The Big New Movie";
  
  var params = {
      TableName:table,
      Item:{
          "year": year,
          "title": title,
          "info":{
              "plot": "Nothing happens at all.",
              "rating": 0
          }
      }
  };
  
  console.log("Adding a new item...");
  docClient.put(params, function(err, data) {
      if (err) {
          console.error("Unable to add item. Error JSON:", JSON.stringify(err, null, 2));
      } else {
          console.log("Added item:", JSON.stringify(data, null, 2));
      }
  });
  </code></pre>
  
  <p><strong>Promise async Version - assume the wrapping function is marked async</strong></p>
  
  <pre><code>var docClient = new AWS.DynamoDB.DocumentClient();
  
  var table = "Movies";
  
  var year = 2015;
  var title = "The Big New Movie";
  
  var params = {
      TableName:table,
      Item:{
          "year": year,
          "title": title,
          "info":{
              "plot": "Nothing happens at all.",
              "rating": 0
          }
      }
  };
  const result: any = await dynamoDb.put(params).promise()
  console.log(result) 
  </code></pre>