Code cleanup (#1461)

* Code cleanup

* Fix flux tests

* Fix checkstyle errors

* Fix compile error

collection-pipeline/src/main/java/com/iluwatar/collectionpipeline/Car.java

@@ -87,10 +87,7 @@ public class Car {
     } else if (!model.equals(other.model)) {
       return false;
     }
-    if (year != other.year) {
-      return false;
-    }
-    return true;
+    return year == other.year;
   }
 
   public String getMake() {

collection-pipeline/src/main/java/com/iluwatar/collectionpipeline/Person.java

@@ -29,7 +29,7 @@ import java.util.List;
  * A Person class that has the list of cars that the person owns and use.
  */
 public class Person {
-  private List<Car> cars;
+  private final List<Car> cars;
 
   /**
    * Constructor to create an instance of person.

collection-pipeline/src/test/java/com/iluwatar/collectionpipeline/AppTest.java

@@ -37,7 +37,7 @@ import org.slf4j.LoggerFactory;
 public class AppTest {
   private static final Logger LOGGER = LoggerFactory.getLogger(AppTest.class);
 
-  private List<Car> cars = CarFactory.createCars();
+  private final List<Car> cars = CarFactory.createCars();
 
   @Test
   public void testGetModelsAfter2000UsingFor() {