Review changes in Test Cases

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

@@ -45,6 +45,52 @@ public class Car {
     this.category = category;
   }
 
+  @Override
+  public int hashCode() {
+    final int prime = 31;
+    int result = 1;
+    result = prime * result + ((category == null) ? 0 : category.hashCode());
+    result = prime * result + ((make == null) ? 0 : make.hashCode());
+    result = prime * result + ((model == null) ? 0 : model.hashCode());
+    result = prime * result + year;
+    return result;
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) {
+      return true;
+    }
+    if (obj == null) {
+      return false;
+    }
+    if (getClass() != obj.getClass()) {
+      return false;
+    }
+    Car other = (Car) obj;
+    if (category != other.category) {
+      return false;
+    }
+    if (make == null) {
+      if (other.make != null) {
+        return false;
+      }
+    } else if (!make.equals(other.make)) {
+      return false;
+    }
+    if (model == null) {
+      if (other.model != null) {
+        return false;
+      }
+    } else if (!model.equals(other.model)) {
+      return false;
+    }
+    if (year != other.year) {
+      return false;
+    }
+    return true;
+  }
+
   public String getMake() {
     return make;
   }