lib/plugins/aws/package/compile/events/schedule/index.js/AwsCompileScheduledEvents/buildValidationErrorMessage
class AwsCompileScheduledEvents:  buildValidationErrorMessage(functionName) {
    return [
      `"rate" property for schedule event is missing or invalid in function ${functionName}.`,
      ' The correct syntax is: `schedule: rate(10 minutes)`, `schedule: cron(0 12 * * ? *)`',
      ' OR an object with "rate" property.',
      ' Please check the docs for more info:',
      ' https://serverless.com/framework/docs/providers/aws/events/schedule/',
    ].join('');
  }