function getVersionFromSpec(spec) {
  if (!_.isNil(spec) && _.has(spec, 'swagger')) {
    return spec.swagger;
  }
  if (!_.isNil(spec) && _.has(spec, 'openapi')) {
    return spec.openapi;
  }
}
Gets the version of a parsed Spec
@param {object} spec The parsed openapi spec
@returns {object} The bundling rules related with the spec