feat: support s3 request templates

Author: mfogel

lib/apiGateway/schema.js

@@ -260,9 +260,14 @@ const proxiesSchemas = {
           .keys({ 'integration.request.path.object': Joi.string().required() })
           .required(),
         then: Joi.forbidden(),
-        otherwise: key.required()
+        otherwise: Joi.when('request', {
+          is: request.required(),
+          then: key,
+          otherwise: key.required()
+        })
       }),
-      requestParameters
+      requestParameters,
+      request
     })
   }),
   sns: Joi.object({

lib/package/s3/compileMethodsToS3.js

@@ -159,6 +159,13 @@ module.exports = {
       RequestParameters: _.merge(requestParams, http.requestParameters)
     }
 
+    const customRequestTemplates = _.get(http, ['request', 'template'])
+
+    if (!_.isEmpty(customRequestTemplates)) {
+      integration.PassthroughBehavior = 'NEVER'
+      integration.RequestTemplates = customRequestTemplates
+    }
+
     const integrationResponse = {
       IntegrationResponses: [
         {