We now validate query method invocations to check method parameters whether they accept null values and reject execution if null values are not supported. We derive nullability support from repository interfaces declared using Kotlin and Spring's NonNullApi/Nullable annotations.
We also check whether a query method can return null. If a query method returns null which isn't supposed to do so, then we throw EmptyResultDataAccessException to prevent null return values.
interface UserRepository extends Repository<User, String> {
List<User> findByLastname(@Nullable String firstname);
@Nullable
User findByFirstnameAndLastname(String firstname, String lastname);
}
interface UserRepository : Repository<User, String> {
fun findByLastname(username: String?): List<User>
fun findByFirstnameAndLastname(firstname: String, lastname: String): User?
}
Original pull request: #241.
fcf97e1e71