LoganSquare VS jackson-modules-java8

I liked https://github.com/bluelinelabs/LoganSquare for example, but annotation processors are hard to maintain. Look at libraries like Mortar-Architect https://github.com/lukaspili/Mortar-architect or Blade https://github.com/FrantisekGazo/Blade or even better Permissions-Dispatcher https://github.com/permissions-dispatcher/PermissionsDispatcher/issues/775 which actually breaks builds after certain Kotlin versions.

Ah I forgot you have to explicitly register the JavaTimeModule, did you do that when creating the object mapper? See https://github.com/FasterXML/jackson-modules-java8

Here's the source code. It uses the ISO-88601 format without timezone modifier, e.g. "2021-10-25T00:23:12" – or in other words the same format as LocalDateTime.toString().

Let's say you have a REST API that returns customers. The service layer would talk to repository layer which would talk to the entity layer to ultimately get the Customer object. It makes the most sense just to return Optional to the controller, and using a certain serialization module, the Optional would automatically get translated to JSON.