code: private static Class<?> convert(Class<?> unboxed) {
          Class<?> boxed = BOXED_EQUIVALENT.get(unboxed);
          return boxed == null ? unboxed : boxed;
      }
docs: Converts primitive types to their boxed equivalent {@link int} converts
  to {@link Integer}. If not conversion was found the parameter is returned
  without modification.
  
  @param unboxed the type to convert
  @return the boxed type