title: Apollo Vue (using AWS Amplify/AppSync) Graphql query does not pull parent data
body: <p>I am using AWS AppSync (via Apollo Vue) and I have the following graphql model.</p>
  
  <pre><code>type Service @model
  {
    id: ID!
    name: String!
    description: String!
  }
  
  type Session @model
  {
    id: ID!
    service: Service @connection(keyName: "ServiceSessionConnection")
  }
  </code></pre>
  
  <p>Service table resolver:</p>
  
  <pre><code>#set( $limit = $util.defaultIfNull($context.args.limit, 10) )
  #set( $query = {
    "expression": "#connectionAttribute = :connectionAttribute",
    "expressionNames": {
        "#connectionAttribute": "serviceSessionsId"
    },
    "expressionValues": {
        ":connectionAttribute": {
            "S": "$context.source.id"
      }
    }
  } )
  {
    "version": "2017-02-28",
    "operation": "Query",
    "query":   $util.toJson($query),
    "scanIndexForward":   #if( $context.args.sortDirection )
      #if( $context.args.sortDirection == "ASC" )
  true
      #else
  false
      #end
    #else
  true
    #end,
    "filter":   #if( $context.args.filter )
  $util.transform.toDynamoDBFilterExpression($ctx.args.filter)
    #else
  null
    #end,
    "limit": $limit,
    "nextToken":   #if( $context.args.nextToken )
  $util.toJson($context.args.nextToken)
    #else
  null
    #end,
    "index": "gsi-Service.sessions"
  }
  </code></pre>
  
  <p>Session table resolver:</p>
  
  <pre><code>{
    "version": "2017-02-28",
    "operation": "GetItem",
    "key": {
        "id": $util.dynamodb.toDynamoDBJson($util.defaultIfNullOrBlank($ctx.source.sessionServiceId, "___xamznone____"))
    }
  }
  </code></pre>
  
  <p>I am creating the following records:</p>
  
  <pre><code>mutation createService {
     createService {
       id: "Id1",
       name: "name",
       description: "desc"
     }
  }
  mutation createSession {
     createSession {
       id: "Id2",
       serviceSessionsId: "Id1" //note: serviceSessionsId created part of relationship (it is part of the resolved code above!), and I am setting that to parent ID (in this case serviceId value "Id1")
     }
  } 
  </code></pre>
  
  <p>I am trying to run following child table (Session) query with parent (Service) data:</p>
  
  <pre><code>query listSessions {
    listSessions {
      items {
        id,
        serviceId,
        service {        //retuns null data
          id,            //retuns null data
          name,          //retuns null data
          description.   //retuns null data
        }
      }
    }
  }
  </code></pre>
  
  <p>I am not getting parent (Service object) data. Since I am modeled child-parent <code>@connection(keyName: "ServiceSessionConnection")</code> relationship, shouldn't I expect parent data in the query result? Am I missing anything? What else needs to be configured to have relationship data in the query result?  </p>