Fix warnings 2 (#1130)

* FIX: warnings (add generics, overrides, fix imports) - should be no effecive code change

* replaced deprecated methods by default methods

* FIX: more compiler warnings

* FIX more warnings - no code changes

* FIX: deprecated call to JsonParseException

* Remove unused code, check unused variables

src/test/java/org/tests/transaction/TestNested.java

@@ -33,9 +33,6 @@ public class TestNested extends BaseTestCase {
 
   private void willFail() {
     Ebean.executeCall(() -> {
-      if (false) {
-        return 123;
-      }
       throw new RuntimeException("test runnable rollback");
     });
   }