`FallThrough` should not add break when `switch` is last statement in a method requiring a `return`

In the following case

  public class A {
      public int m(int i) {
          switch (i) {
              case 0:
                  if (true) return i;
              default:
                  throw new IllegalStateException();
          }
      }
  }

the FallThrough recipe should not add a break statement after the if. The resulting code doesn't compile. Instead it would be better to add a // fall through comment here.

Locate the FallThrough recipe and its related tests in the repository, then reproduce the Java example from the issue. Verify the transformation no longer inserts a break after the conditional return when the switch is the final statement of a method requiring a return; done means the result compiles and uses a fall-through comment instead.