diff --git a/src/main/kotlin/fr/dcproject/component/article/database/Article.kt b/src/main/kotlin/fr/dcproject/component/article/database/Article.kt
index d758c16..b0d1596 100644
--- a/src/main/kotlin/fr/dcproject/component/article/database/Article.kt
+++ b/src/main/kotlin/fr/dcproject/component/article/database/Article.kt
@@ -48,7 +48,7 @@ data class ArticleForView(
     val lastVersion: Boolean = false
 }
 
-interface ArticleForUpdateI<C : CitizenRef> : ArticleI, ArticleWithTitleI, VersionableId, TargetI, CreatedBy<C> {
+sealed interface ArticleForUpdateI<C : CitizenRef> : ArticleI, ArticleWithTitleI, VersionableId, TargetI, CreatedBy<C> {
     val anonymous: Boolean
     val content: String
     val description: String
@@ -56,13 +56,13 @@ interface ArticleForUpdateI<C : CitizenRef> : ArticleI, ArticleWithTitleI, Versi
     val workgroup: WorkgroupRef?
 }
 
-class ArticleForUpdate(
+data class ArticleForUpdate(
     override val id: UUID = UUID.randomUUID(),
     override val title: String,
     override val anonymous: Boolean = true,
     override val content: String,
     override val description: String,
-    tags: List<String> = emptyList(),
+    val tags: Set<String> = emptySet(),
     override val draft: Boolean = false,
     override val createdBy: CitizenRef,
     override val workgroup: WorkgroupRef? = null,
@@ -71,12 +71,10 @@ class ArticleForUpdate(
 ) : ArticleRef(id),
     ArticleForUpdateI<CitizenRef>,
     ArticleAuthI<CitizenRef>,
-    VersionableId {
-    val tags: List<String> = tags.distinct()
-}
+    VersionableId
 
-class ArticleForListing(
-    id: UUID? = null,
+data class ArticleForListing(
+    override val id: UUID = UUID.randomUUID(),
     override val title: String,
     override val createdBy: CitizenCreator,
     override val workgroup: WorkgroupCart? = null,
@@ -90,7 +88,7 @@ class ArticleForListing(
     CreatedAt by CreatedAt.Imp(),
     CreatedBy<CitizenCartI>
 
-interface ArticleForListingI : ArticleWithTitleI, CreatedBy<CitizenCartI> {
+sealed interface ArticleForListingI : ArticleWithTitleI, CreatedBy<CitizenCartI> {
     val workgroup: WorkgroupCartI?
 }
 
@@ -98,13 +96,13 @@ open class ArticleRef(
     id: UUID? = null
 ) : ArticleI, TargetRef(id)
 
-interface ArticleI : EntityI, TargetI
+sealed interface ArticleI : EntityI, TargetI
 
-interface ArticleWithTitleI : ArticleI {
+sealed interface ArticleWithTitleI : ArticleI {
     val title: String
 }
 
-interface ArticleAuthI<U : CitizenI> :
+sealed interface ArticleAuthI<U : CitizenI> :
     ArticleI,
     CreatedBy<U>,
     DeletedAt {
diff --git a/src/main/kotlin/fr/dcproject/component/article/routes/UpsertArticle.kt b/src/main/kotlin/fr/dcproject/component/article/routes/UpsertArticle.kt
index 8f018f1..82ddb83 100644
--- a/src/main/kotlin/fr/dcproject/component/article/routes/UpsertArticle.kt
+++ b/src/main/kotlin/fr/dcproject/component/article/routes/UpsertArticle.kt
@@ -37,7 +37,7 @@ object UpsertArticle {
             val anonymous: Boolean = true,
             val content: String,
             val description: String,
-            val tags: List<String> = emptyList(),
+            val tags: Set<String> = emptySet(),
             val draft: Boolean = false,
             val versionId: UUID,
             val workgroup: WorkgroupRef? = null,
diff --git a/src/main/kotlin/fr/dcproject/component/auth/database/User.kt b/src/main/kotlin/fr/dcproject/component/auth/database/User.kt
index fe43d14..c25d40d 100644
--- a/src/main/kotlin/fr/dcproject/component/auth/database/User.kt
+++ b/src/main/kotlin/fr/dcproject/component/auth/database/User.kt
@@ -9,35 +9,45 @@ import io.ktor.auth.Principal
 import org.joda.time.DateTime
 import java.util.UUID
 
-class UserForCreate(
-    id: UUID = UUID.randomUUID(),
-    username: String,
+data class UserForCreate(
+    override val id: UUID = UUID.randomUUID(),
+    override val username: String,
     override val password: String,
-    blockedAt: DateTime? = null,
-    roles: List<Roles> = emptyList()
-) : User(id, username, blockedAt, roles),
-    UserWithPasswordI
+    override val blockedAt: DateTime? = null,
+    override val roles: Set<Roles> = emptySet()
+) : UserForViewI,
+    UserWithPasswordI,
+    CreatedAt by CreatedAt.Imp(),
+    UpdatedAt by UpdatedAt.Imp()
 
-open class User(
-    id: UUID = UUID.randomUUID(),
-    override var username: String,
-    var blockedAt: DateTime? = null,
-    var roles: List<Roles> = emptyList()
+data class User(
+    override val id: UUID = UUID.randomUUID(),
+    override val username: String,
+    override val blockedAt: DateTime? = null,
+    override val roles: Set<Roles> = emptySet()
 ) : UserRef(id),
+    UserForViewI,
     UserWithUsername,
     CreatedAt by CreatedAt.Imp(),
     UpdatedAt by UpdatedAt.Imp()
 
+sealed interface UserForViewI :
+    UserI,
+    UserWithUsername,
+    UserForAuthI,
+    CreatedAt,
+    UpdatedAt
+
 class UserCreator(
     id: UUID = UUID.randomUUID(),
     override val username: String,
 ) : UserRef(id), UserWithUsername
 
-interface UserWithUsername : UserI {
+sealed interface UserWithUsername : UserI {
     val username: String
 }
 
-interface UserWithPasswordI : UserI {
+sealed interface UserWithPasswordI : UserI {
     val password: String
 }
 
@@ -51,11 +61,11 @@ open class UserRef(
     id: UUID = UUID.randomUUID()
 ) : UserI, Entity(id)
 
-interface UserI : EntityI, Principal {
+sealed interface UserI : EntityI, Principal {
     enum class Roles { ROLE_USER, ROLE_ADMIN }
 }
 
-interface UserForAuthI : UserI {
-    var roles: List<Roles>
-    var blockedAt: DateTime?
+sealed interface UserForAuthI : UserI {
+    val roles: Set<Roles>
+    val blockedAt: DateTime?
 }
diff --git a/src/main/kotlin/fr/dcproject/component/auth/routes/Register.kt b/src/main/kotlin/fr/dcproject/component/auth/routes/Register.kt
index 0daa29a..d3f6fe0 100644
--- a/src/main/kotlin/fr/dcproject/component/auth/routes/Register.kt
+++ b/src/main/kotlin/fr/dcproject/component/auth/routes/Register.kt
@@ -91,7 +91,7 @@ object Register {
             user = UserForCreate(
                 username = user.username,
                 password = user.password,
-                roles = listOf(UserI.Roles.ROLE_USER)
+                roles = setOf(UserI.Roles.ROLE_USER)
             )
         )
 
diff --git a/src/main/kotlin/fr/dcproject/component/citizen/database/Citizen.kt b/src/main/kotlin/fr/dcproject/component/citizen/database/Citizen.kt
index 14d0597..6fef54e 100644
--- a/src/main/kotlin/fr/dcproject/component/citizen/database/Citizen.kt
+++ b/src/main/kotlin/fr/dcproject/component/citizen/database/Citizen.kt
@@ -17,19 +17,19 @@ import fr.postgresjson.entity.Serializable
 import org.joda.time.DateTime
 import java.util.UUID
 
-class CitizenForCreate(
+data class CitizenForCreate(
     val name: Name,
     val email: String,
     val birthday: DateTime,
     val voteAnonymous: Boolean = true,
     val followAnonymous: Boolean = true,
     override val user: UserForCreate,
-    id: UUID = UUID.randomUUID(),
+    override val id: UUID = UUID.randomUUID(),
 ) : CitizenI,
-    CitizenRefWithUser(id, user),
+    CitizenWithUserI by CitizenRefWithUser(id, user),
     CreatedAt by CreatedAt.Imp()
 
-class Citizen(
+data class Citizen(
     override val id: UUID = UUID.randomUUID(),
     override val name: Name,
     override val email: String,
@@ -37,7 +37,7 @@ class Citizen(
     override val voteAnonymous: Boolean = true,
     override val followAnonymous: Boolean = true,
     override val user: User,
-    deletedAt: DateTime? = null
+    override val deletedAt: DateTime? = null
 ) : CitizenWithEmail,
     CitizenCreatorI,
     CitizenWithUserI,
@@ -62,10 +62,11 @@ data class CitizenCreator(
     override val user: UserCreator,
     override val deletedAt: DateTime? = null
 ) : CitizenCreatorI,
-    CitizenRefWithUser(id, user),
+    CitizenI,
+    CitizenWithUserI by CitizenRefWithUser(id, user),
     DeletedAt by DeletedAt.Imp(deletedAt)
 
-interface CitizenCreatorI : CitizenWithUserI, CitizenWithEmail, CitizenCartI, DeletedAt {
+sealed interface CitizenCreatorI : CitizenWithUserI, CitizenWithEmail, CitizenCartI, DeletedAt {
     override val id: UUID
     override val name: Name
     override val email: String
@@ -75,8 +76,8 @@ interface CitizenCreatorI : CitizenWithUserI, CitizenWithEmail, CitizenCartI, De
     override val deletedAt: DateTime?
 }
 
-class CitizenCart(
-    id: UUID = UUID.randomUUID(),
+data class CitizenCart(
+    override val id: UUID = UUID.randomUUID(),
     override val name: Name,
     override val user: UserRef,
     override val deletedAt: DateTime? = null,
@@ -84,13 +85,13 @@ class CitizenCart(
     CitizenCartI,
     DeletedAt by DeletedAt.Imp(deletedAt)
 
-interface CitizenCartI : CitizenI, CitizenWithUserI {
+sealed interface CitizenCartI : CitizenI, CitizenWithUserI {
     val name: Name
 }
 
-open class CitizenRefWithUser(
-    id: UUID = UUID.randomUUID(),
-    override val user: UserRef
+data class CitizenRefWithUser(
+    override val id: UUID = UUID.randomUUID(),
+    override val user: UserI
 ) : CitizenWithUserI,
     CitizenRef(id)
 
@@ -99,7 +100,7 @@ open class CitizenRef(
 ) : TargetRef(id),
     CitizenI
 
-interface CitizenI : EntityI, TargetI {
+sealed interface CitizenI : EntityI, TargetI {
     data class Name(
         override val firstName: String,
         override val lastName: String,
@@ -114,10 +115,10 @@ interface CitizenI : EntityI, TargetI {
     }
 }
 
-interface CitizenWithUserI : CitizenI {
+sealed interface CitizenWithUserI : CitizenI {
     val user: UserI
 }
 
-interface CitizenWithEmail : CitizenI {
+sealed interface CitizenWithEmail : CitizenI {
     val email: String
 }
diff --git a/src/main/kotlin/fr/dcproject/component/comment/generic/database/Comment.kt b/src/main/kotlin/fr/dcproject/component/comment/generic/database/Comment.kt
index fdb95f0..e2f30cd 100644
--- a/src/main/kotlin/fr/dcproject/component/comment/generic/database/Comment.kt
+++ b/src/main/kotlin/fr/dcproject/component/comment/generic/database/Comment.kt
@@ -16,8 +16,8 @@ import fr.dcproject.component.vote.entity.VotableImp
 import org.joda.time.DateTime
 import java.util.UUID
 
-class CommentForView<T : TargetI, C : CitizenCreatorI>(
-    id: UUID = UUID.randomUUID(),
+data class CommentForView<T : TargetI, C : CitizenCreatorI>(
+    override val id: UUID = UUID.randomUUID(),
     override val createdBy: C,
     override val target: T,
     override var content: String,
@@ -30,7 +30,7 @@ class CommentForView<T : TargetI, C : CitizenCreatorI>(
     CommentWithTargetI<T>,
     CreatedBy<C> by CreatedBy.Imp(createdBy),
     UpdatedAt by UpdatedAt.Imp(),
-    DeletedAt by DeletedAt.Imp(),
+    DeletedAt,
     Votable by VotableImp(),
     TargetI {
     constructor(
@@ -50,9 +50,9 @@ open class CommentForUpdate<T : TargetI, C : CitizenI>(
     override val createdBy: C,
     override val target: T,
     open var content: String,
-    override val parent: CommentParent<T>? = null,
+    override val parent: CommentParentI<T>? = null,
     override val deletedAt: DateTime? = null
-) : CommentParent<T>(id, deletedAt, target),
+) : CommentParentI<T> by CommentParent(id, deletedAt, target),
     CommentWithParentI<T>,
     ExtraI<T, C>,
     CommentWithTargetI<T>,
@@ -62,7 +62,7 @@ open class CommentForUpdate<T : TargetI, C : CitizenI>(
     TargetI {
     constructor(
         createdBy: C,
-        parent: CommentParent<T>,
+        parent: CommentParentI<T>,
         content: String,
         id: UUID? = null,
     ) : this(
@@ -74,21 +74,21 @@ open class CommentForUpdate<T : TargetI, C : CitizenI>(
     )
 }
 
-open class CommentParent<T : TargetI>(
+data class CommentParent<T : TargetI>(
     override val id: UUID,
     override val deletedAt: DateTime?,
     override val target: T
 ) : CommentRef(id),
     CommentParentI<T>
 
-interface CommentParentI<T : TargetI> : CommentI, DeletedAt, CommentWithTargetI<T>
+sealed interface CommentParentI<T : TargetI> : CommentI, DeletedAt, CommentWithTargetI<T>
 
 interface CommentWithTargetI<T : TargetI> : CommentI, TargetI, HasTarget<T>
 
 interface CommentWithParentI<T : TargetI> {
-    val parent: CommentParent<T>?
+    val parent: CommentParentI<T>?
 }
 
 open class CommentRef(id: UUID = UUID.randomUUID()) : CommentI, TargetRef(id)
 
-interface CommentI : EntityI
+sealed interface CommentI : EntityI
diff --git a/src/main/kotlin/fr/dcproject/component/comment/generic/database/CommentRepository.kt b/src/main/kotlin/fr/dcproject/component/comment/generic/database/CommentRepository.kt
index 8a86a7b..1f140eb 100644
--- a/src/main/kotlin/fr/dcproject/component/comment/generic/database/CommentRepository.kt
+++ b/src/main/kotlin/fr/dcproject/component/comment/generic/database/CommentRepository.kt
@@ -32,26 +32,21 @@ abstract class CommentRepositoryAbs<T : TargetI>(override var requester: Request
         parentId: UUID,
         page: Int = 1,
         limit: Int = 50
-    ): Paginated<CommentForView<T, CitizenCreatorI>> {
-        return requester.run {
-            getFunction("find_comments_by_parent")
-                .select<CommentForView<T, CitizenCreator>>(
-                    page,
-                    limit,
-                    "parent_id" to parentId
-                )
-                as Paginated<CommentForView<T, CitizenCreatorI>>
-        }
-    }
+    ): Paginated<CommentForView<T, CitizenCreatorI>> = requester
+        .getFunction("find_comments_by_parent")
+        .select<CommentForView<T, CitizenCreator>>(
+            page,
+            limit,
+            "parent_id" to parentId
+        )
+        as Paginated<CommentForView<T, CitizenCreatorI>>
 
     open fun findByTarget(
         target: EntityI,
         page: Int = 1,
         limit: Int = 50,
         sort: String = "createdAt"
-    ): Paginated<CommentForView<T, CitizenCreatorI>> {
-        return findByTarget(target.id, page, limit, sort)
-    }
+    ): Paginated<CommentForView<T, CitizenCreatorI>> = findByTarget(target.id, page, limit, sort)
 
     open fun findByTarget(
         targetId: UUID,
@@ -85,41 +80,33 @@ abstract class CommentRepositoryAbs<T : TargetI>(override var requester: Request
 }
 
 class CommentRepository(requester: Requester) : CommentRepositoryAbs<TargetRef>(requester) {
-    override fun findById(id: UUID): CommentForView<TargetRef, CitizenCreatorI>? {
-        return requester
-            .getFunction("find_comment_by_id")
-            .selectOne<CommentForView<TargetRef, CitizenCreator>>(mapOf("id" to id))
-            as CommentForView<TargetRef, CitizenCreatorI>?
-    }
+    override fun findById(id: UUID): CommentForView<TargetRef, CitizenCreatorI>? = requester
+        .getFunction("find_comment_by_id")
+        .selectOne<CommentForView<TargetRef, CitizenCreator>>(mapOf("id" to id))
+        as CommentForView<TargetRef, CitizenCreatorI>?
 
     override fun findByCitizen(
         citizen: CitizenI,
         page: Int,
         limit: Int
-    ): Paginated<CommentForView<TargetRef, CitizenCreatorI>> {
-        return requester.run {
-            getFunction("find_comments_by_citizen")
-                .select<CommentForView<TargetRef, CitizenCreator>>(
-                    page,
-                    limit,
-                    "created_by_id" to citizen.id
-                ) as Paginated<CommentForView<TargetRef, CitizenCreatorI>>
-        }
-    }
+    ): Paginated<CommentForView<TargetRef, CitizenCreatorI>> = requester
+        .getFunction("find_comments_by_citizen")
+        .select<CommentForView<TargetRef, CitizenCreator>>(
+            page,
+            limit,
+            "created_by_id" to citizen.id
+        ) as Paginated<CommentForView<TargetRef, CitizenCreatorI>>
 
     override fun findByParent(
         parentId: UUID,
         page: Int,
         limit: Int
-    ): Paginated<CommentForView<TargetRef, CitizenCreatorI>> {
-        return requester.run {
-            getFunction("find_comments_by_parent")
-                .select<CommentForView<TargetRef, CitizenCreator>>(
-                    page,
-                    limit,
-                    "parent_id" to parentId
-                )
-                as Paginated<CommentForView<TargetRef, CitizenCreatorI>>
-        }
-    }
+    ): Paginated<CommentForView<TargetRef, CitizenCreatorI>> = requester
+        .getFunction("find_comments_by_parent")
+        .select<CommentForView<TargetRef, CitizenCreator>>(
+            page,
+            limit,
+            "parent_id" to parentId
+        )
+        as Paginated<CommentForView<TargetRef, CitizenCreatorI>>
 }
diff --git a/src/main/kotlin/fr/dcproject/component/follow/database/Follow.kt b/src/main/kotlin/fr/dcproject/component/follow/database/Follow.kt
index aeafd6c..78ed7c7 100644
--- a/src/main/kotlin/fr/dcproject/component/follow/database/Follow.kt
+++ b/src/main/kotlin/fr/dcproject/component/follow/database/Follow.kt
@@ -8,19 +8,18 @@ import fr.dcproject.common.entity.HasTarget
 import fr.dcproject.common.entity.TargetI
 import fr.dcproject.component.citizen.database.CitizenCreator
 import fr.dcproject.component.citizen.database.CitizenI
-import fr.dcproject.component.citizen.database.CitizenRef
 import java.util.UUID
 
-open class FollowForView<T : TargetI>(
-    id: UUID = UUID.randomUUID(),
+data class FollowForView<T : TargetI>(
+    override val id: UUID = UUID.randomUUID(),
     override val createdBy: CitizenCreator,
     override var target: T
-) : ExtraI<T, CitizenRef>,
+) : ExtraI<T, CitizenI>,
     FollowRef(id),
-    Created<CitizenRef> by Created.Imp(createdBy)
+    Created<CitizenI> by Created.Imp(createdBy)
 
-class FollowForUpdate<T : TargetI, C : CitizenI>(
-    id: UUID = UUID.randomUUID(),
+data class FollowForUpdate<T : TargetI, C : CitizenI>(
+    override val id: UUID = UUID.randomUUID(),
     override val target: T,
     override val createdBy: C
 ) : FollowRef(id),
@@ -31,4 +30,4 @@ open class FollowRef(
     override val id: UUID
 ) : FollowI
 
-interface FollowI : EntityI
+sealed interface FollowI : EntityI
diff --git a/src/main/kotlin/fr/dcproject/component/notification/NotificationMessage.kt b/src/main/kotlin/fr/dcproject/component/notification/NotificationMessage.kt
index 0b7c985..611713f 100644
--- a/src/main/kotlin/fr/dcproject/component/notification/NotificationMessage.kt
+++ b/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")
diff --git a/src/main/kotlin/fr/dcproject/component/notification/email/content/ArticleNotificationEmailContent.kt b/src/main/kotlin/fr/dcproject/component/notification/email/content/ArticleNotificationEmailContent.kt
index 2d634ca..0d61b82 100644
--- a/src/main/kotlin/fr/dcproject/component/notification/email/content/ArticleNotificationEmailContent.kt
+++ b/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,
diff --git a/src/main/kotlin/fr/dcproject/component/notification/email/content/CitizenNotificationEmailContent.kt b/src/main/kotlin/fr/dcproject/component/notification/email/content/CitizenNotificationEmailContent.kt
index af1a5dc..2d259a3 100644
--- a/src/main/kotlin/fr/dcproject/component/notification/email/content/CitizenNotificationEmailContent.kt
+++ b/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,
diff --git a/src/main/kotlin/fr/dcproject/component/opinion/database/Opinion.kt b/src/main/kotlin/fr/dcproject/component/opinion/database/Opinion.kt
index 56864a7..cf761e8 100644
--- a/src/main/kotlin/fr/dcproject/component/opinion/database/Opinion.kt
+++ b/src/main/kotlin/fr/dcproject/component/opinion/database/Opinion.kt
@@ -13,8 +13,8 @@ import fr.dcproject.component.citizen.database.CitizenI
 import fr.dcproject.component.citizen.database.CitizenRef
 import java.util.UUID
 
-open class Opinion<T : TargetI>(
-    id: UUID = UUID.randomUUID(),
+data class Opinion<T : TargetI>(
+    override val id: UUID = UUID.randomUUID(),
     override val createdBy: CitizenCreator,
     override val target: T,
     val choice: OpinionChoice
@@ -39,4 +39,4 @@ open class OpinionRef(
     override val id: UUID
 ) : OpinionI, TargetRef(id)
 
-interface OpinionI : EntityI
+sealed interface OpinionI : EntityI
diff --git a/src/main/kotlin/fr/dcproject/component/opinion/entity/Opinionable.kt b/src/main/kotlin/fr/dcproject/component/opinion/entity/Opinionable.kt
index 61a2684..d3a983f 100644
--- a/src/main/kotlin/fr/dcproject/component/opinion/entity/Opinionable.kt
+++ b/src/main/kotlin/fr/dcproject/component/opinion/entity/Opinionable.kt
@@ -7,6 +7,4 @@ interface Opinionable {
     val opinions: Opinions
 }
 
-class OpinionableImp : Opinionable {
-    override var opinions: OpinionsMutable = mutableMapOf()
-}
+data class OpinionableImp(override var opinions: OpinionsMutable = mutableMapOf()) : Opinionable
diff --git a/src/main/kotlin/fr/dcproject/component/views/dto/ViewAggregation.kt b/src/main/kotlin/fr/dcproject/component/views/dto/ViewAggregation.kt
index 41b1b93..5336ac6 100644
--- a/src/main/kotlin/fr/dcproject/component/views/dto/ViewAggregation.kt
+++ b/src/main/kotlin/fr/dcproject/component/views/dto/ViewAggregation.kt
@@ -2,7 +2,7 @@ package fr.dcproject.component.views.dto
 
 import fr.dcproject.component.views.entity.ViewAggregation
 
-class ViewAggregation(
+data class ViewAggregation(
     val total: Int,
     val unique: Int
 ) {
diff --git a/src/main/kotlin/fr/dcproject/component/views/entity/ViewAggregation.kt b/src/main/kotlin/fr/dcproject/component/views/entity/ViewAggregation.kt
index f9e5f95..ffdfb6f 100644
--- a/src/main/kotlin/fr/dcproject/component/views/entity/ViewAggregation.kt
+++ b/src/main/kotlin/fr/dcproject/component/views/entity/ViewAggregation.kt
@@ -3,7 +3,7 @@ package fr.dcproject.component.views.entity
 import fr.dcproject.common.entity.UpdatedAt
 import fr.postgresjson.entity.EntityI
 
-class ViewAggregation(
+data class ViewAggregation(
     val total: Int,
     val unique: Int
 ) : EntityI,
diff --git a/src/main/kotlin/fr/dcproject/component/vote/database/Vote.kt b/src/main/kotlin/fr/dcproject/component/vote/database/Vote.kt
index 0fc6af0..648e165 100644
--- a/src/main/kotlin/fr/dcproject/component/vote/database/Vote.kt
+++ b/src/main/kotlin/fr/dcproject/component/vote/database/Vote.kt
@@ -12,8 +12,8 @@ import fr.dcproject.component.citizen.database.CitizenCreatorI
 import fr.dcproject.component.citizen.database.CitizenI
 import java.util.UUID
 
-class VoteForView<T : TargetI>(
-    id: UUID = UUID.randomUUID(),
+data class VoteForView<T : TargetI>(
+    override val id: UUID = UUID.randomUUID(),
     override val createdBy: CitizenCreator,
     override val target: T,
     val note: Int,
@@ -30,7 +30,7 @@ class VoteForView<T : TargetI>(
     }
 }
 
-class VoteForUpdate<T : TargetI, C : CitizenI>(
+data class VoteForUpdate<T : TargetI, C : CitizenI>(
     override val id: UUID = UUID.randomUUID(),
     override val note: Int,
     override val target: T,
diff --git a/src/main/kotlin/fr/dcproject/component/vote/dto/VoteAggregation.kt b/src/main/kotlin/fr/dcproject/component/vote/dto/VoteAggregation.kt
index b109cb7..bb8da12 100644
--- a/src/main/kotlin/fr/dcproject/component/vote/dto/VoteAggregation.kt
+++ b/src/main/kotlin/fr/dcproject/component/vote/dto/VoteAggregation.kt
@@ -2,10 +2,18 @@ package fr.dcproject.component.vote.dto
 
 import fr.dcproject.component.vote.entity.Votable
 
-class VoteAggregation(parent: Votable) {
-    val up: Int = parent.votes.up
-    val neutral: Int = parent.votes.neutral
-    val down: Int = parent.votes.down
-    val total: Int = parent.votes.total
-    val score: Int = parent.votes.score
+data class VoteAggregation(
+    val up: Int,
+    val neutral: Int,
+    val down: Int,
+    val total: Int,
+    val score: Int
+) {
+    constructor(parent: Votable) : this(
+        up = parent.votes.up,
+        neutral = parent.votes.neutral,
+        down = parent.votes.down,
+        total = parent.votes.total,
+        score = parent.votes.score
+    )
 }
diff --git a/src/main/kotlin/fr/dcproject/component/vote/entity/Votable.kt b/src/main/kotlin/fr/dcproject/component/vote/entity/Votable.kt
index 6971e80..82fb028 100644
--- a/src/main/kotlin/fr/dcproject/component/vote/entity/Votable.kt
+++ b/src/main/kotlin/fr/dcproject/component/vote/entity/Votable.kt
@@ -4,6 +4,6 @@ interface Votable {
     val votes: VoteAggregation
 }
 
-class VotableImp : Votable {
+data class VotableImp(
     override val votes: VoteAggregation = VoteAggregation()
-}
+) : Votable
diff --git a/src/main/kotlin/fr/dcproject/component/workgroup/database/Workgroup.kt b/src/main/kotlin/fr/dcproject/component/workgroup/database/Workgroup.kt
index 9e3a4ed..13979a5 100644
--- a/src/main/kotlin/fr/dcproject/component/workgroup/database/Workgroup.kt
+++ b/src/main/kotlin/fr/dcproject/component/workgroup/database/Workgroup.kt
@@ -43,17 +43,17 @@ data class WorkgroupForUpdate<C : CitizenWithUserI>(
     WorkgroupForUpdateI<C>,
     CreatedBy<C> by CreatedBy.Imp(createdBy)
 
-interface WorkgroupForUpdateI<C : CitizenWithUserI> : WorkgroupWithAuthI<C>, WorkgroupCartI, CreatedBy<C> {
+sealed interface WorkgroupForUpdateI<C : CitizenWithUserI> : WorkgroupWithAuthI<C>, WorkgroupCartI, CreatedBy<C> {
     val description: String
     val logo: String?
 }
 
-class WorkgroupCart(
+data class WorkgroupCart(
     override val id: UUID,
     override val name: String
 ) : WorkgroupCartI
 
-interface WorkgroupCartI : EntityI {
+sealed interface WorkgroupCartI : EntityI {
     val name: String
 }
 
@@ -61,7 +61,7 @@ open class WorkgroupRef(
     id: UUID? = null
 ) : Entity(id ?: UUID.randomUUID()), WorkgroupI
 
-interface WorkgroupWithAuthI<Z : CitizenWithUserI> : WorkgroupWithMembersI<Z>, CreatedBy<Z>, DeletedAt {
+sealed interface WorkgroupWithAuthI<Z : CitizenWithUserI> : WorkgroupWithMembersI<Z>, CreatedBy<Z>, DeletedAt {
     val anonymous: Boolean
 
     fun isMember(user: UserI): Boolean = members.isMember(user)
@@ -70,11 +70,11 @@ interface WorkgroupWithAuthI<Z : CitizenWithUserI> : WorkgroupWithMembersI<Z>, C
     fun hasRole(expectedRole: Role, user: UserI): Boolean = members.hasRole(expectedRole, user)
     fun hasRole(expectedRole: Role, citizen: CitizenI): Boolean = members.hasRole(expectedRole, citizen)
 
-    fun getRoles(user: UserI): List<Role> = members.getRoles(user)
-    fun getRoles(citizen: CitizenI): List<Role> = members.getRoles(citizen)
+    fun getRoles(user: UserI): Collection<Role> = members.getRoles(user)
+    fun getRoles(citizen: CitizenI): Collection<Role> = members.getRoles(citizen)
 }
 
-interface WorkgroupWithMembersI<Z : CitizenI> : WorkgroupI {
+sealed interface WorkgroupWithMembersI<Z : CitizenI> : WorkgroupI {
     val members: List<Member<Z>>
 
     class Member<C : CitizenI>(
@@ -90,24 +90,24 @@ interface WorkgroupWithMembersI<Z : CitizenI> : WorkgroupI {
     }
 }
 
-fun List<CitizenI>.hasCitizen(citizen: CitizenI): Boolean = this.map { it.id }.contains(citizen.id)
+fun Collection<CitizenI>.hasCitizen(citizen: CitizenI): Boolean = this.map { it.id }.contains(citizen.id)
 
-fun <Z : CitizenWithUserI> List<Member<Z>>.isMember(user: UserI): Boolean =
+fun <Z : CitizenWithUserI> Collection<Member<Z>>.isMember(user: UserI): Boolean =
     map { it.citizen.user.id }.contains(user.id)
 
-fun <Z : CitizenI> List<Member<Z>>.isMember(citizen: CitizenI): Boolean =
+fun <Z : CitizenI> Collection<Member<Z>>.isMember(citizen: CitizenI): Boolean =
     map { it.citizen.id }.contains(citizen.id)
 
-fun <Z : CitizenI> List<Member<Z>>.hasRole(expectedRole: Role, citizen: CitizenI): Boolean =
+fun <Z : CitizenI> Collection<Member<Z>>.hasRole(expectedRole: Role, citizen: CitizenI): Boolean =
     any { member -> member.citizen.id == citizen.id && member.roles.any { it == expectedRole } }
 
-fun <Z : CitizenWithUserI> List<Member<Z>>.hasRole(expectedRole: Role, user: UserI): Boolean =
+fun <Z : CitizenWithUserI> Collection<Member<Z>>.hasRole(expectedRole: Role, user: UserI): Boolean =
     any { member -> member.citizen.user.id == user.id && member.roles.any { it == expectedRole } }
 
-fun <Z : CitizenWithUserI> List<Member<Z>>.getRoles(user: UserI): List<Role> =
+fun <Z : CitizenWithUserI> Collection<Member<Z>>.getRoles(user: UserI): Collection<Role> =
     firstOrNull { it.citizen.user.id == user.id }?.roles ?: emptyList()
 
-fun <Z : CitizenWithUserI> List<Member<Z>>.getRoles(citizen: CitizenI): List<Role> =
+fun <Z : CitizenWithUserI> Collection<Member<Z>>.getRoles(citizen: CitizenI): Collection<Role> =
     firstOrNull { it.citizen.id == citizen.id }?.roles ?: emptyList()
 
 interface WorkgroupI : EntityI
diff --git a/src/test/kotlin/functional/ViewTest.kt b/src/test/kotlin/functional/ViewTest.kt
index 92795ff..5a89c8d 100644
--- a/src/test/kotlin/functional/ViewTest.kt
+++ b/src/test/kotlin/functional/ViewTest.kt
@@ -20,8 +20,8 @@ import org.junit.jupiter.api.TestInstance
 import org.junit.jupiter.api.TestInstance.Lifecycle.PER_CLASS
 import org.koin.ktor.ext.get
 import java.util.UUID
+import kotlin.time.Duration.Companion.seconds
 import kotlin.time.ExperimentalTime
-import kotlin.time.seconds
 
 @KtorExperimentalLocationsAPI
 @ExperimentalCoroutinesApi
@@ -78,7 +78,7 @@ class ViewTest {
             )
 
             /* Retry because ES is not sync ! */
-            retry(10, 0.3.seconds) {
+            retry(10, seconds(0.3)) {
                 /* Get view */
                 val afterView = viewRepository.getViewsCount(article)
 
diff --git a/src/test/kotlin/integration/Check auth on all routes.kt b/src/test/kotlin/integration/Check auth on all routes.kt
index a148b1e..702c48e 100644
--- a/src/test/kotlin/integration/Check auth on all routes.kt	
+++ b/src/test/kotlin/integration/Check auth on all routes.kt	
@@ -35,7 +35,7 @@ class `Check auth on all routes` : BaseTest() {
                         /* Send request to check security */
                         sendRequest(
                             path.buildUrl(pathName, methodName, api.context), /* Replace route to real URL */
-                            HttpMethod.parse(methodName.toUpperCase()) /* Convert http method name to enum */
+                            HttpMethod.parse(methodName.lowercase()) /* Convert http method name to enum */
                         )
                     }
             }.let { requests ->
diff --git a/src/test/kotlin/integration/steps/given/Auth.kt b/src/test/kotlin/integration/steps/given/Auth.kt
index 7401d3b..6cb4d05 100644
--- a/src/test/kotlin/integration/steps/given/Auth.kt
+++ b/src/test/kotlin/integration/steps/given/Auth.kt
@@ -13,7 +13,7 @@ fun TestApplicationRequest.`authenticated as`(
     firstName: String,
     lastName: String,
 ): Citizen {
-    val username = "$firstName-$lastName".toLowerCase()
+    val username = "$firstName-$lastName".lowercase()
     val repo: CitizenRepository by lazy<CitizenRepository> { GlobalContext.get().get() }
     val citizen = repo.findByUsername(username) ?: error("Citizen not exist with username $username")
     val algorithm = GlobalContext.get().get<JwtConfig>().algorithm
diff --git a/src/test/kotlin/integration/steps/given/Citizen.kt b/src/test/kotlin/integration/steps/given/Citizen.kt
index cb763c6..8bdb138 100644
--- a/src/test/kotlin/integration/steps/given/Citizen.kt
+++ b/src/test/kotlin/integration/steps/given/Citizen.kt
@@ -14,7 +14,7 @@ import java.util.UUID
 fun TestApplicationEngine.`Given I have citizen`(
     firstName: String,
     lastName: String,
-    email: String = ("$firstName-$lastName".toLowerCase()) + "@dc-project.fr",
+    email: String = ("$firstName-$lastName".lowercase()) + "@dc-project.fr",
     id: String = UUID.randomUUID().toString(),
     callback: Citizen.() -> Unit = {}
 ): Citizen? {
@@ -22,7 +22,7 @@ fun TestApplicationEngine.`Given I have citizen`(
 
     val user = UserForCreate(
         id = id.toUUID(),
-        username = "$firstName-$lastName".toLowerCase(),
+        username = "$firstName-$lastName".lowercase(),
         password = "Azerty123!",
     )
     val citizen = CitizenForCreate(
diff --git a/src/test/kotlin/integration/steps/given/Workgroup.kt b/src/test/kotlin/integration/steps/given/Workgroup.kt
index b6aac03..b433551 100644
--- a/src/test/kotlin/integration/steps/given/Workgroup.kt
+++ b/src/test/kotlin/integration/steps/given/Workgroup.kt
@@ -62,7 +62,7 @@ private fun createWorkgroup(
     val creatorName = createdBy ?: CitizenI.Name("Paul", "Langevin")
     val creator = citizenRepository.findByName(creatorName) ?: run {
         val username = ("username" + UUID.randomUUID().toString())
-            .toLowerCase().replace(' ', '-')
+            .lowercase().replace(' ', '-')
         val user = UserForCreate(
             username = username,
             password = "Azerty123!",
diff --git a/src/test/kotlin/integration/steps/then/schema.kt b/src/test/kotlin/integration/steps/then/schema.kt
index fe04cf0..85cc9f1 100644
--- a/src/test/kotlin/integration/steps/then/schema.kt
+++ b/src/test/kotlin/integration/steps/then/schema.kt
@@ -46,7 +46,7 @@ fun TestApplicationResponse.operation(route: String? = null, callback: Operation
             .firstOrNull { uri.matches(it.replace("""\{[^{}]+}""".toRegex(), "[^/]+").toRegex()) }
 
         api.getPath(path)
-            ?.getOperation(httpMethod.value.toLowerCase())
+            ?.getOperation(httpMethod.value.lowercase())
             ?.apply {
                 this.callback(api, uri)
             }
@@ -59,7 +59,7 @@ fun TestApplicationResponse.`And the schema response body must be valid`(content
         /* Validate Response */
         this.apply {
             val status = call.response.status()
-            val httpMethod = call.request.httpMethod.value.toUpperCase()
+            val httpMethod = call.request.httpMethod.value.lowercase()
             val responseContent: JsonNode = if (content != null)
                 ObjectMapper().readTree(content)
             else TextNode("")
@@ -79,7 +79,7 @@ fun TestApplicationResponse.`And the schema parameters must be valid`() {
     operation { api, uri ->
         /* Validate Request URL */
         this.apply {
-            val methodName = call.request.httpMethod.value.toUpperCase()
+            val methodName = call.request.httpMethod.value.lowercase()
             Url(call.request.uri).parameters.forEach { parameter: String, values: List<String> ->
                 val schema = getParametersIn(api.context, "query")
                     ?.firstOrNull { it.name == parameter }?.schema
@@ -103,7 +103,7 @@ fun TestApplicationResponse.`And the schema parameters must be valid`() {
  * Validate request body
  */
 fun TestApplicationResponse.`And the schema request body must be valid`(body: String) {
-    operation { api, uri ->
+    operation { api, _ ->
         requestBody
             .getContentMediaType(call.request.contentType().toString())
             .schema
diff --git a/src/test/kotlin/integration/steps/when/request.kt b/src/test/kotlin/integration/steps/when/request.kt
index fe71e72..ee2ec46 100644
--- a/src/test/kotlin/integration/steps/when/request.kt
+++ b/src/test/kotlin/integration/steps/when/request.kt
@@ -15,15 +15,15 @@ import io.ktor.server.testing.TestApplicationRequest
 import io.ktor.server.testing.setBody
 
 enum class Validate(override val bit: Long) : BitMaskI {
-    NONE(0),
-    REQUEST_BODY(1),
-    REQUEST_PARAM(2),
-    REQUEST_HEADER(4),
-    REQUEST(1 + 2 + 4),
-    RESPONSE_BODY(8),
-    RESPONSE_HEADER(16),
-    RESPONSE(8 + 16),
-    ALL((1 + 2 + 4) + (8 + 16));
+    NONE(0L),
+    REQUEST_BODY(1L),
+    REQUEST_PARAM(2L),
+    REQUEST_HEADER(4L),
+    REQUEST(1L + 2L + 4L),
+    RESPONSE_BODY(8L),
+    RESPONSE_HEADER(16L),
+    RESPONSE(8L + 16L),
+    ALL((1L + 2L + 4L) + (8L + 16L));
 
     operator fun unaryMinus(): BitMaskI = ALL - BitMask(this.bit)
 }
diff --git a/src/test/kotlin/unit/security/Article Access Control.kt b/src/test/kotlin/unit/security/Article Access Control.kt
index 9f9389b..df859b7 100644
--- a/src/test/kotlin/unit/security/Article Access Control.kt	
+++ b/src/test/kotlin/unit/security/Article Access Control.kt	
@@ -41,7 +41,7 @@ internal class `Article Access Control` {
     private val einstein = CitizenCart(
         user = User(
             username = "albert-einstein",
-            roles = listOf(UserI.Roles.ROLE_USER)
+            roles = setOf(UserI.Roles.ROLE_USER)
         ),
         name = CitizenI.Name("Albert", "Einstein")
     )
diff --git a/src/test/kotlin/unit/security/Citizen Access Control.kt b/src/test/kotlin/unit/security/Citizen Access Control.kt
index 153356c..715c897 100644
--- a/src/test/kotlin/unit/security/Citizen Access Control.kt	
+++ b/src/test/kotlin/unit/security/Citizen Access Control.kt	
@@ -23,14 +23,14 @@ internal class `Citizen Access Control` {
     private val tesla = CitizenCart(
         user = User(
             username = "nicolas-tesla",
-            roles = listOf(UserI.Roles.ROLE_USER)
+            roles = setOf(UserI.Roles.ROLE_USER)
         ),
         name = CitizenI.Name("Nicolas", "Tesla")
     )
     private val einstein = CitizenCart(
         user = User(
             username = "albert-einstein",
-            roles = listOf(UserI.Roles.ROLE_USER)
+            roles = setOf(UserI.Roles.ROLE_USER)
         ),
         name = CitizenI.Name("Albert", "Einstein")
     )
@@ -38,7 +38,7 @@ internal class `Citizen Access Control` {
     private val curie = CitizenCart(
         user = User(
             username = "marie-curie",
-            roles = listOf(UserI.Roles.ROLE_USER)
+            roles = setOf(UserI.Roles.ROLE_USER)
         ),
         name = CitizenI.Name("Marie", "Curie"),
         deletedAt = DateTime.now()
diff --git a/src/test/kotlin/unit/security/Comment Access Control.kt b/src/test/kotlin/unit/security/Comment Access Control.kt
index e2d9260..f380292 100644
--- a/src/test/kotlin/unit/security/Comment Access Control.kt	
+++ b/src/test/kotlin/unit/security/Comment Access Control.kt	
@@ -30,7 +30,7 @@ internal class `Comment Access Control` {
     private val tesla = Citizen(
         user = User(
             username = "nicolas-tesla",
-            roles = listOf(UserI.Roles.ROLE_USER)
+            roles = setOf(UserI.Roles.ROLE_USER)
         ),
         birthday = DateTime.now(),
         email = "tesla@best.com",
@@ -40,7 +40,7 @@ internal class `Comment Access Control` {
         id = UUID.fromString("319f1226-8f47-4df3-babd-2c7671ad0fbc"),
         user = User(
             username = "albert-einstein",
-            roles = listOf(UserI.Roles.ROLE_USER)
+            roles = setOf(UserI.Roles.ROLE_USER)
         ),
         birthday = DateTime.now(),
         email = "einstein@best.com",
diff --git a/src/test/kotlin/unit/security/Follow Access Control.kt b/src/test/kotlin/unit/security/Follow Access Control.kt
index c093a7e..c644869 100644
--- a/src/test/kotlin/unit/security/Follow Access Control.kt	
+++ b/src/test/kotlin/unit/security/Follow Access Control.kt	
@@ -36,7 +36,7 @@ internal class `Follow Access Control` {
     private val tesla2 = Citizen(
         user = User(
             username = "nicolas-tesla",
-            roles = listOf(UserI.Roles.ROLE_USER)
+            roles = setOf(UserI.Roles.ROLE_USER)
         ),
         birthday = DateTime.now(),
         email = "tesla@best.com",
@@ -67,7 +67,7 @@ internal class `Follow Access Control` {
         id = UUID.fromString("319f1226-8f47-4df3-babd-2c7671ad0fbc"),
         user = User(
             username = "albert-einstein",
-            roles = listOf(UserI.Roles.ROLE_USER)
+            roles = setOf(UserI.Roles.ROLE_USER)
         ),
         birthday = DateTime.now(),
         email = "einstein@best.com",
diff --git a/src/test/kotlin/unit/security/Vote Access Control.kt b/src/test/kotlin/unit/security/Vote Access Control.kt
index e10f69a..5bf784a 100644
--- a/src/test/kotlin/unit/security/Vote Access Control.kt	
+++ b/src/test/kotlin/unit/security/Vote Access Control.kt	
@@ -30,7 +30,7 @@ internal class `Vote Access Control` {
         id = UUID.fromString("a1e35c99-9d33-4fb4-9201-58d7071243bb"),
         user = User(
             username = "nicolas-tesla",
-            roles = listOf(UserI.Roles.ROLE_USER)
+            roles = setOf(UserI.Roles.ROLE_USER)
         ),
         birthday = DateTime.now(),
         email = "tesla@best.com",
@@ -51,7 +51,7 @@ internal class `Vote Access Control` {
         id = UUID.fromString("319f1226-8f47-4df3-babd-2c7671ad0fbc"),
         user = User(
             username = "albert-einstein",
-            roles = listOf(UserI.Roles.ROLE_USER)
+            roles = setOf(UserI.Roles.ROLE_USER)
         ),
         birthday = DateTime.now(),
         email = "einstein@best.com",
diff --git a/src/test/resources/sql/test.sh b/src/test/resources/sql/test.sh
index 83767dd..2b17577 100644
--- a/src/test/resources/sql/test.sh
+++ b/src/test/resources/sql/test.sh
@@ -15,15 +15,15 @@ fi
 case $opt in
   "RESET DB")
       awk 'FNR==1{print "--------------------"}1' \
-        ../../main/resources/sql/migrations/*.down.sql \
-        ../../main/resources/sql/migrations/*.up.sql > ./allSQL.sql
+        ../../../main/resources/sql/migrations/*.down.sql \
+        ../../../main/resources/sql/migrations/*.up.sql > ./allSQL.sql
       docker exec -i dc-project_postgresql_test psql test test -q -b -v "ON_ERROR_STOP=1" < ./allSQL.sql
       rm ./allSQL.sql
       ;;
   "All")
       echo "Start ALL tests"
       awk 'FNR==1{print "--------------------"}1' \
-        ../../main/resources/sql/functions/*/*.sql \
+        ../../../main/resources/sql/functions/*/*.sql \
         ./fixtures/*.sql \
         ./*.sql > ./allSQL.sql
       docker exec -i dc-project_postgresql_test psql test test -q -b -v "ON_ERROR_STOP=1" < ./allSQL.sql
@@ -34,7 +34,7 @@ case $opt in
   *)
     echo "Start tests $opt"
     awk 'FNR==1{print "--------------------"}1' \
-      ../../main/resources/sql/functions/*/*.sql \
+      ../../../main/resources/sql/functions/*/*.sql \
       ./fixtures/*.sql \
       ./"$opt".sql > ./allSQL.sql
     docker exec -i dc-project_postgresql_test psql test test -q -b -v "ON_ERROR_STOP=1" < ./allSQL.sql