Feature Request: Provide `DestinationTopic.Properties#isRetryTopic()` method

[vivekragunathan]

Based on @tomazfernandes's request, filing this feature request for a DestinationTopic.Properties#isRetryTopic() method. There are currently isMainTopic and isDltTopic methods but not a isRetryTopic method.

Workaround today is:

Boolean isRetryTopic = !properties.isMainTopic() && !properties.isDltTopic();

[tomazfernandes]

Thanks @vivekragunathan - also, feel free to provide a PR if you'd like.

[vivekragunathan]

Yes sure ... that PR for some bed time stretching tonight