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

visitor/src/test/java/com/iluwatar/visitor/UnitTest.java

@@ -55,7 +55,7 @@ public abstract class UnitTest<U extends Unit> {
   }
 
   @Test
-  public void testAccept() throws Exception {
+  public void testAccept() {
     final Unit[] children = new Unit[5];
     Arrays.setAll(children, (i) -> mock(Unit.class));