Multiple minors fix and improve

use data class for entity
Add sealed on entity interfaces
Replace listOf() by setOf() instead of deduplicate
use interface instead of EntityRef
replace .toLowerCase() to .lowercase()
fix test.sh

src/main/kotlin/fr/dcproject/component/notification/NotificationMessage.kt

@@ -53,11 +53,11 @@ open class NotificationMessage(
 }
 
 open class EntityNotificationMessage <E : Entity> (
-    val target: E,
+    open val target: E,
     type: String,
     val action: String
 ) : NotificationMessage(type)
 
-class ArticleUpdateNotificationMessage(
-    target: ArticleForView
+data class ArticleUpdateNotificationMessage(
+    override val target: ArticleForView
 ) : EntityNotificationMessage<ArticleForView>(target, "article", "update")

src/main/kotlin/fr/dcproject/component/notification/email/content/ArticleNotificationEmailContent.kt

@@ -3,7 +3,7 @@ package fr.dcproject.component.notification.email.content
 import fr.dcproject.component.article.database.ArticleWithTitleI
 import fr.dcproject.component.citizen.database.Citizen
 
-class ArticleNotificationEmailContent(
+data class ArticleNotificationEmailContent(
     private val citizen: Citizen,
     private val target: ArticleWithTitleI,
     private val domain: String,

src/main/kotlin/fr/dcproject/component/notification/email/content/CitizenNotificationEmailContent.kt

@@ -2,7 +2,7 @@ package fr.dcproject.component.notification.email.content
 
 import fr.dcproject.component.citizen.database.Citizen
 
-class CitizenNotificationEmailContent(
+data class CitizenNotificationEmailContent(
     private val citizen: Citizen,
     private val target: Citizen,
     private val domain: String,