code: public static final int getTotalCapacity(WsByteBuffer[] list) {
          if (null == list) {
              return 0;
          }
          int cap = 0;
          for (int i = 0; i < list.length; i++) {
              if (list[i] != null) {
                  cap += list[i].capacity();
              }
          }
          return cap;
      }
docs: Find out the total capacity in an array of buffers. A null or empty
  list will return 0.
  
  @param list
  @return int