API-GW async integration with Lambda

MyApi:
  Type: 'AWS::Serverless::Api'
  Properties:
    StageName: '<stage name>'
    DefinitionBody:
      swagger: '2.0'
      info:
        title: '<title>'
      paths:
        /<somepath>:
          <method>:
            x-amazon-apigateway-integration:
              type: AWS
              requestParameters:
                integration.request.header.X-Amz-Invocation-Type: '''Event'''
              httpMethod: <method>
              uri: '<lambda uri>'