todo/src/main/java/ru/kamask/pet/todo/model/Identifiable.java

@@ -0,0 +1,5 @@
+package ru.kamask.pet.todo.model;
+
+public interface Identifiable {
+    int getId();
+}

todo/src/main/java/ru/kamask/pet/todo/model/Task.java

@@ -1,6 +1,6 @@
 package ru.kamask.pet.todo.model;
 
-public abstract class Task {
+public abstract class Task implements Identifiable{
     private static int nextId = 1;
 
     protected int id;
@@ -11,10 +11,15 @@ public abstract class Task {
         this.title = title;
     }
 
-    public int id() {
+    @Override
+    public int getId() {
         return id;
     }
 
+    public int id() {
+        return getId();
+    }
+
     @Override
     public String toString() {
         return String.format("Задача: id - %d, title: \"%s\"", id, title);