docs: public String toDelta() {
          StringBuilder text = new StringBuilder();
          for (Change aDiff : getChangeList()) {
              switch (aDiff.operation) {
                  case INSERT:
                      try {
                          text.append("+").append(URLEncoder.encode(aDiff.text, "UTF-8")
                                                            .replace('+', ' ')).append("\t");
                      } catch (UnsupportedEncodingException e) {
                          // Not likely on modern system.
                          throw new Error("This system does not support UTF-8.", e);
                      }
                      break;
                  case DELETE:
                      text.append("-").append(aDiff.text.length()).append("\t");
                      break;
                  case EQUAL:
                      text.append("=").append(aDiff.text.length()).append("\t");
                      break;
              }
          }
          String delta = text.toString();
          if (delta.length() != 0) {
              // Strip off trailing tab character.
              delta = delta.substring(0, delta.length() - 1);
              delta = Strings.unescapeForEncodeUriCompatability(delta);
          }
          return delta;
      }