Code cleanup (#1461)

* Code cleanup

* Fix flux tests

* Fix checkstyle errors

* Fix compile error

semaphore/src/main/java/com/iluwatar/semaphore/Fruit.java

@@ -35,7 +35,7 @@ public class Fruit {
     ORANGE, APPLE, LEMON
   }
 
-  private FruitType type;
+  private final FruitType type;
 
   public Fruit(FruitType type) {
     this.type = type;

semaphore/src/main/java/com/iluwatar/semaphore/FruitBowl.java

@@ -31,7 +31,7 @@ import java.util.List;
  */
 public class FruitBowl {
 
-  private List<Fruit> fruit = new ArrayList<>();
+  private final List<Fruit> fruit = new ArrayList<>();
 
   /**
    * Returns the amount of fruits left in bowl.

semaphore/src/main/java/com/iluwatar/semaphore/FruitShop.java

@@ -31,7 +31,7 @@ public class FruitShop {
   /**
    * The FruitBowl instances stored in the class.
    */
-  private FruitBowl[] bowls = {
+  private final FruitBowl[] bowls = {
       new FruitBowl(),
       new FruitBowl(),
       new FruitBowl()
@@ -40,7 +40,7 @@ public class FruitShop {
   /**
    * Access flags for each of the FruitBowl instances.
    */
-  private boolean[] available = {
+  private final boolean[] available = {
       true,
       true,
       true
@@ -49,7 +49,7 @@ public class FruitShop {
   /**
    * The Semaphore that controls access to the class resources.
    */
-  private Semaphore semaphore;
+  private final Semaphore semaphore;
 
   /**
    * FruitShop constructor.