No property found for type… custom Spring Data repository

The problem here is that you are creating FilterRepositoryImpl but you are using it in UserRepository. You need to create UserRepositoryImpl to make this work.

Read this doc for more detail

Basically

public interface UserRepositoryCustom {
    List<User> filterBy(String role);
}

public class UserRepositoryImpl implements UserRepositoryCustom {
...
}

public interface UserRepository extends JpaRepository<User, String>, UserRepositoryCustom {
...
}

Spring Data 2.x update
This answer was written for Spring 1.x. As Matt Forsythe pointed out, the naming expectations changed with Spring Data 2.0. The implementation changed from the-final-repository-interface-name-with-an-additional-Impl-suffix to the-custom-interface-name-with-an-additional-Impl-suffix.

So in this case, the name of the implementation would be: UserRepositoryCustomImpl.