No property found for type... custom Spring Data repository

I'm trying to implement a custom Spring repository. I have the interface:

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

the implementation:

public class FilterRepositoryImpl implements FilterRepositoryCustom {
...
}

and the "main" repository, extending my custom repository:

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

I'm using Spring Boot and, according to the docs:

By default, Spring Boot will enable JPA repository support and look in the package (and its subpackages) where @SpringBootApplication is located.

When I run my application, I get this error:

org.springframework.data.mapping.PropertyReferenceException: No property filterBy found for type User!

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.