code: public boolean contains(Object e) {
          if (e == null)
              return false;
          Class<?> eClass = e.getClass();
          if (eClass != elementType && eClass.getSuperclass() != elementType)
              return false;
  
          int eOrdinal = ((Enum<?>)e).ordinal();
          return (elements[eOrdinal >>> 6] & (1L << eOrdinal)) != 0;
      }
docs: Returns <tt>true</tt> if this set contains the specified element.
  
  @param e element to be checked for containment in this collection
  @return <tt>true</tt> if this set contains the specified element