Update PolygonFactory.java (eugenp#3108)

Author: pivovarit

core-java/src/main/java/com/baeldung/designpatterns/creational/factory/PolygonFactory.java

@@ -11,12 +11,12 @@ public Polygon getPolygon(int numberOfSides) {
         if(numberOfSides == 5) {
             return new Pentagon();
         }
-        if(numberOfSides == 4) {
+        if(numberOfSides == 7) {
             return new Heptagon();
         }
         else if(numberOfSides == 8) {
             return new Octagon();
         }
         return null;
     }
-}
+}