code: public final String getFullString(final int len, String charsetName) {
          if (position + len > origin + limit) throw new IllegalArgumentException("limit excceed: "
                                                                                  + (position + len - origin));
  
          try {
              String string = new String(buffer, position, len, charsetName);
              position += len;
              return string;
          } catch (UnsupportedEncodingException e) {
              throw new IllegalArgumentException("Unsupported encoding: " + charsetName, e);
          }
      }
docs: Return next fix-length string from buffer without null-terminate
  checking. Fix bug #17 {@link https
  ://github.com/AlibabaTech/canal/issues/17 }