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

lazy-loading/src/main/java/com/iluwatar/lazy/loading/Java8Holder.java

@@ -37,7 +37,7 @@ public class Java8Holder {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(Java8Holder.class);
 
-  private Supplier<Heavy> heavy = () -> createAndCacheHeavy();
+  private Supplier<Heavy> heavy = this::createAndCacheHeavy;
 
   public Java8Holder() {
     LOGGER.info("Java8Holder created");