I believe the attached test case reproduces the issue hibernate-orm-5.1.10.final-HHH-3917.zip. It is similar to a setup we currently have in our codebase where I noticed the eager-fetch when using @NotFound.

We have an entity Parent which contains a ManyToOne relationship with an Address. Addresses can come in multiple types. We were playing with mapping all of the possible subclasses of Address in Parent, using @NotFound to return null when it isn't found. This should result in only 1 of the 2 fields ever returning a value. This works, but the address is loaded eagerly even when set to FetchType.LAZY.