code: protected String generateParameterString(List<Parameter> parameters) {
      if (parameters == null) {
        return "";
      }
  
      StringBuilder parameterStringBuilder = new StringBuilder();
      boolean first = true;
  
      for (Parameter parameter : parameters) {
        if (first) {
          first = false;
        } else {
          parameterStringBuilder.append("&");
        }
  
        parameterStringBuilder.append(urlEncode(parameter.name));
        parameterStringBuilder.append("=");
        parameterStringBuilder.append(urlEncode(parameter.value));
      }
  
      return parameterStringBuilder.toString();
    }
docs: For a list of parameters, generate a URL query string.
  <p>
  Does not include a leading "?" character.
  
  @param parameters
  The parameters to stringify.
  @return A URL query string representation of the given {@code parameters}.