add solution Collections task 3707

Author: oldSorcerer

4.JavaCollections/src/com/javarush/task/task37/task3707/AmigoSet.java

@@ -7,9 +7,8 @@
 
 public class AmigoSet<E> extends AbstractSet<E> implements Serializable, Cloneable, Set<E> {
 
-    private static final Object PRESENT = new Object();
-
     private transient HashMap<E, Object> map;
+    private static final Object PRESENT = new Object();
 
     public AmigoSet() {
         this.map = new HashMap<>();
@@ -35,7 +34,6 @@ public int size() {
         return map.size();
     }
 
-
     @Override
     public boolean isEmpty() {
         return map.isEmpty();