docs: update memento

memento/src/main/java/com/iluwatar/memento/App.java

@@ -67,7 +67,7 @@ public class App {
     states.add(star.getMemento());
     star.timePasses();
     LOGGER.info(star.toString());
-    while (states.size() > 0) {
+    while (!states.isEmpty()) {
       star.setMemento(states.pop());
       LOGGER.info(star.toString());
     }

memento/src/main/java/com/iluwatar/memento/Star.java

@@ -24,6 +24,9 @@
  */
 package com.iluwatar.memento;
 
+import lombok.Getter;
+import lombok.Setter;
+
 /**
  * Star uses "mementos" to store and restore state.
  */
@@ -85,34 +88,12 @@ public class Star {
   /**
    * StarMemento implementation.
    */
+  @Getter
+  @Setter
   private static class StarMementoInternal implements StarMemento {
 
     private StarType type;
     private int ageYears;
     private int massTons;
-
-    public StarType getType() {
-      return type;
-    }
-
-    public void setType(StarType type) {
-      this.type = type;
-    }
-
-    public int getAgeYears() {
-      return ageYears;
-    }
-
-    public void setAgeYears(int ageYears) {
-      this.ageYears = ageYears;
-    }
-
-    public int getMassTons() {
-      return massTons;
-    }
-
-    public void setMassTons(int massTons) {
-      this.massTons = massTons;
-    }
   }
 }