dependencies: #2449 bump maven-checkstyle-plugin from 3.1.0 to 3.2.0 + resolve chec… (#2464)

* #2449 bump maven-checkstyle-plugin from 3.1.0 to 3.2.0 + resolve checkstyle issues

* remove FileSelectorJFrame.java to resolve checkstyle issue

* remove FileSelectorJFrame.java to resolve checkstyle issue

* remove FileSelectorJFrame.java to resolve checkstyle issue

* add refactored file with correct filename to resolve checkstyle issue

* add the test data

* change filenames from JFrame to Jframe for checkstyle

* fix code smell from  sonar report

* add new testcases to improve the test coverage

* remove code smell

special-case/src/main/java/com/iluwatar/specialcase/OutOfStock.java

@@ -27,6 +27,9 @@ package com.iluwatar.specialcase;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+/**
+ * Receipt view for showing out of stock message.
+ */
 public class OutOfStock implements ReceiptViewModel {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(OutOfStock.class);