title: How to enable "ApiKeyRequired" property in SAM without explicit swagger definition?
body: <p>In cloudformation, <code>AWS::ApiGateway::Method</code> has a boolean property <code>ApiKeyRequired</code> . How can i achieve the same in SAM ?</p>
  
  <p>I know that we can enable using explicit swagger Configuration.  which is like this</p>
  
  <pre><code>    {
      "swagger": "2.0",
      "info": {
          "version": "1.0",
          "title": {
                "Ref": "AWS::StackName"
              }
      },
      "x-amazon-apigateway-api-key-source": "HEADER",
      "paths": {
          "/": {
              "get": {
                  "x-amazon-apigateway-integration": {
                      "httpMethod": "POST",
                      "type": "aws_proxy",
                      "uri": {
                      "Fn::Sub": "arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${GetHelloWorld.Arn}/invocations"
                    }
                  },
                  "responses": {},
                  "security": [
                      {
                          "api_key": []
                      }
                  ]
              }
          }
      },
      "securityDefinitions": {
          "api_key": {
              "type": "apiKey",
              "name": "x-api-key",
              "in": "header"
          }
      }
  }
  </code></pre>
  
  <p>Cant it possible with implicit API call in SAM rather than explicitly passing the <code>AWS::Serverless::Api</code> ? Because the swagger code is okay for less endpoints and becomes complex once endpoints got increased. Is there any flag like <code>APIkeyRequired</code> like we have in <code>Cloudformation</code> ?</p>
  
  <p>Any help is appreciated
  Thanks</p>