code: func ValidateScheme(name string, apiDef *raml.APIDefinition) bool {
  	if name == "" || name == "null" {
  		return false
  	}
  	if ss, ok := apiDef.GetSecurityScheme(name); ok {
  		return ss.Type == Oauth2
  	}
  	return false
  }
docs: // validate security scheme:
  // - not empty
  // - not 'null'
  // - oauth2 -> we only support oauth2 now