JPA Lazy loading is not working in Spring boot

Hibernate Session exists within method with @Transactional. Passing entity outside Service class is a bad practise because session is being closed after leaving your search method. On the other hand your entity contains lazy initialised collections, which cannot be pulled once session is closed.

The good practise is to map entity onto transport object and return those transport objects from service (not raw entities).

Most likely you are debugging while still being inside the service, thus while the transaction is still active and lazy loading can be triggered (any method called on a lazy element triggered the fetch from the database).

The problem is that lazy loading cannot occur while being outside of the transaction. And Jackson is parsing your entity definitely outside the boundaries of one.

You either should fetch all the required dependencies when building your specification or try with the @Transactional on the resource level (but try that as of last resort).

Just so that you know, LAZY fetching strategy is only a hint.. not a mandatory action. Eager is mandatory:

The LAZY strategy is a hint to the persistence provider runtime that data should be fetched lazily when it is first accessed. The implementation is permitted to eagerly fetch data for which the LAZY strategy hint has been specified.

SpringBoot by default has enabled:
spring.jpa.open-in-view = true
That means transaction is always open. Try to disable it.
more information here