title: Indexing document in ElasticSearch Id null failure
body: <p>Good day: </p>
  
  <p>I'm trying to index this document document into ES. I'm currently doing a <strong>POST</strong> for the document creation:</p>
  
  <pre><code>{  
     "name":"facility 3",
     "types":[  
        1
     ],
     "status":1,
     "registrationDate":"0001-01-01T00:00:00",
     "capacity":0,
     "rating":0.0,
     "licenseStatus":0,
     "licenseDate":"0001-01-01T00:00:00",
     "licenseCloseDate":"0001-01-01T00:00:00",
     "address":"10 thomas avenue*",
     "zipCode":"12345",
     "rentLow":0.0,
     "rentHigh":0.0,
     "basePriceLow":0.0,
     "basePriceHigh":0.0,
     "oneTimeFee":0.0,
     "levelOfCareRangeMinimum":0.0,
     "levelOfCareRangeMaximum":0.0,
     "city":"new york city",
     "state":"New York",
     "facilityManagements":[  
        {  
           "userId":"3e85f416-b00a-407e-a34e-05cec99f38b1",
           "operations":1,
           "isOwner":true,
           "isActive":true,
           "createdDate":"2018-06-29T16:08:19.7700068Z",
           "id":"d7db8c5b-24a2-4a5f-a508-1188233b305f"
        }
     ],
     "facilityRequests":[  
        {  
           "userId":"3e85f416-b00a-407e-a34e-05cec99f38b1",
           "createdDate":"2018-06-29T16:08:19.7709542Z",
           "status":1,
           "id":"77cfa81e-0f62-47ff-8956-b15b7c4321f0"
        }
     ],
     "slug":"facility-3-10-thomas-avenue",
     "approved":false,
     "businessLocation":{  
        "lat":40.7143545,
        "lon":-74.0059735
     },
     "serviceAreas":{  
        "coordinates":[  
           [  
              [  
                 0.0,
                 0.0
              ]
           ]
        ],
        "type":"polygon"
     },
     "suggest":{  
        "input":[  
           "new york city",
           "New York",
           "facility",
           "3"
        ]
     }
  }
  </code></pre>
  
  <p>However, this is resulting in the following error <code>id must not be null</code>. I do not get it because, I thought ES would generate the ID in this case. Also, I've index my mapping using NEST:</p>
  
  <pre><code>  var uri = new Uri(ConfigurationManager.AppSettings["ElasticSearch-Node1"]);
              var pool = new SingleNodeConnectionPool(uri);
              //ElasticSearch Client
              string index = ConfigurationManager.AppSettings["ElasticIndex"];
              return new ConnectionSettings(pool).DefaultIndex(index)
                  .DefaultMappingFor&lt;Facility&gt;(m =&gt; m.IndexName(index).TypeName("doc"));
  </code></pre>
  
  <p>Facility has a bunch of other inner nested objects that is being indexed with it. </p>