How to shorten names of query methods in Spring Data JPA Repositories?

Use default Java 8 feature for wrapping, just like so:

interface UserInterface extends JpaRepository<User, Long> {

    // use findOneByEmail instead
    User findOneByDeletedIsFalseAndEmail(String email);
    
    default User findOneByEmail(String email) {
        return findOneByDeletedIsFalseAndEmail(email);
    }
}

See an example.

With Kotlin, you can use extension functions, for example:

interface UserRepository : JpaRepository<User, Long> {

    // use findOneByEmail instead
    fun findOneByDeletedIsFalseAndEmail(email: String): User
}

fun UserRepository.findOneByEmail(email: String) =
    findOneByDeletedIsFalseAndEmail(email)