code: public static Class<?> getBoxingClass(Type t) throws BugError
    {
      Type boxingClass = BOXING_MAP.get(t);
      if(boxingClass == null) {
        if(!BOXING_MAP.values().contains(t)) {
          throw new BugError("Trying to get boxing class from not boxed type.");
        }
        boxingClass = t;
      }
      return (Class<?>)boxingClass;
    }
docs: Get boxing class for requested type. If <code>type</code> is primitive returns related boxing class. If
  <code>type</code> is already a boxing type returns it as it is. It is considered a bug if <code>type</code> is not
  a primitive or a boxing type.
  
  @param t primitive or boxing type.
  @return boxing class representing requested type.
  @throws BugError if <code>type</code> is not a primitive or boxing type.