Fix bootstrap warning: getter methods of lazy classes cannot be final

src/main/kotlin/org/springframework/samples/petclinic/model/BaseEntity.kt

@@ -34,7 +34,7 @@ open class BaseEntity : Serializable {
 
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
-    var id: Int? = null
+    open var id: Int? = null
 
     val isNew: Boolean
         get() = this.id == null

src/main/kotlin/org/springframework/samples/petclinic/model/NamedEntity.kt

@@ -31,7 +31,7 @@ import javax.persistence.MappedSuperclass
 open class NamedEntity : BaseEntity() {
 
     @Column(name = "name")
-    var name: String? = null
+    open var name: String? = null
 
     override fun toString(): String =
             this.name ?: ""