hasEvent method
Implementation
@override
bool hasEvent(String tagName, String eventName) {
  var elementEvents =
      eventSchema[tagName.toLowerCase()] ?? eventSchema['unknown']!;
  return elementEvents.contains(eventName.toLowerCase());
}@override
bool hasEvent(String tagName, String eventName) {
  var elementEvents =
      eventSchema[tagName.toLowerCase()] ?? eventSchema['unknown']!;
  return elementEvents.contains(eventName.toLowerCase());
}