feature #14: create route for follow article

src/main/kotlin/fr/dcproject/entity/Extra.kt

@@ -0,0 +1,22 @@
+package fr.dcproject.entity
+
+import fr.postgresjson.entity.EntityCreatedAt
+import fr.postgresjson.entity.EntityCreatedAtImp
+import fr.postgresjson.entity.EntityI
+import fr.postgresjson.entity.UuidEntity
+import java.util.*
+
+interface ExtraI <T: EntityI<UUID>>:
+    EntityI<UUID>,
+    EntityCreatedAt {
+    var citizen: Citizen
+    var target: T
+}
+
+abstract class Extra<T: EntityI<UUID>>(
+    id: UUID? = UUID.randomUUID(),
+    override var citizen: Citizen
+):
+    ExtraI<T>,
+    UuidEntity(id),
+    EntityCreatedAt by EntityCreatedAtImp()

src/main/kotlin/fr/dcproject/entity/Follow.kt

@@ -0,0 +1,11 @@
+package fr.dcproject.entity
+import fr.postgresjson.entity.EntityI
+import java.util.*
+
+class Follow <T: EntityI<UUID>> (
+    id: UUID = UUID.randomUUID(),
+    citizen: Citizen,
+    override var target: T
+): Extra<T>(id, citizen)
+
+typealias FollowArticleEntity = Follow<Article>