lib/plugins/aws/package/compile/events/schedule/index.js/AwsCompileScheduledEvents/formatInputTransformer
class AwsCompileScheduledEvents:  formatInputTransformer(inputTransformer) {
    if (!inputTransformer.inputTemplate) {
      throw new this.serverless.classes.Error(
        'The inputTemplate key is required when specifying an ' +
        'inputTransformer for a schedule event'
      );
    }
    const cfmOutput = {
      // InputTemplate is required
      InputTemplate: inputTransformer.inputTemplate,
    };
    // InputPathsMap is optional
    if (inputTransformer.inputPathsMap) {
      cfmOutput.InputPathsMap = inputTransformer.inputPathsMap;
    }
    return JSON.stringify(cfmOutput);
  }