Merge remote-tracking branch 'origin/s-morimto' into s-choi

src/main/java/com/example/demo/app/infra/repository/UserRepository.java

@@ -16,5 +16,6 @@ public interface UserRepository extends JpaRepository<UserEntity, Long> {
             String mailAddress,
             String password);
 
+    Optional<UserEntity> findByMailAddress(String mailAddress);
 }