Minor refactorings and code style changes. 1) Removed several use of raw types 2) Removed unnecessary throws clauses 3) Used lambda expressions wherever applicable 4) Used apt assertion methods for readability 5) Use of try with resources wherever applicable 6) Corrected incorrect order of assertXXX arguments

observer/src/test/java/com/iluwatar/observer/generic/ObserverTest.java

@@ -42,7 +42,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
  * @author Jeroen Meulemeester
  */
 @TestInstance(TestInstance.Lifecycle.PER_CLASS)
-public abstract class ObserverTest<O extends Observer> {
+public abstract class ObserverTest<O extends Observer<?, ?, WeatherType>> {
 
   private InMemoryAppender appender;