Code cleanup (#1461)

* Code cleanup

* Fix flux tests

* Fix checkstyle errors

* Fix compile error

proxy/src/test/java/com/iluwatar/proxy/utils/InMemoryAppender.java

@@ -35,7 +35,7 @@ import org.slf4j.LoggerFactory;
  * InMemory Log Appender Util.
  */
 public class InMemoryAppender extends AppenderBase<ILoggingEvent> {
-  private List<ILoggingEvent> log = new LinkedList<>();
+  private final List<ILoggingEvent> log = new LinkedList<>();
 
   public InMemoryAppender(Class clazz) {
     ((Logger) LoggerFactory.getLogger(clazz)).addAppender(this);