code: @SuppressWarnings("unchecked")
      public static Object[] toArray(final Collection<?> c) {
          if (N.isNullOrEmpty(c)) {
              return N.EMPTY_OBJECT_ARRAY;
          }
  
          return c.toArray(new Object[c.size()]);
      }
docs: Returns an empty array if the specified collection is null or empty.
  
  @param c
  @return