You can just add below 4 lines into your POJO:
private Instant lastModifiedDate;
private Instant createdDate;
and then add below line to your application:
the database will manage it for you.
however if you give ID when you are creating a new document, then the database will consider you are updating, so you will never get "createDate"
as above link mentioned, you have 2 workaround, i suggest you use @version. you just need to add below to your POJO:
private String version;
Next, you need to make sure you copy them over when you update them otherwise you may lost them.