code: private String substitute(String uri) {
      	List<String> params = extractRequiredParamsInURI(uri);
      	for (String param: params) {
      		if (param.equals(PARAMS)) {
      			uri = uri.replace("{" + PARAMS +"}", Utils.urlEncode(getParamsURI()));
      		}
      		else {
      			uri = uri.replace("{" + param + "}", (String)commandParams.get(param));
      		}
      	}
          return uri;
      }
docs: Substitute the params with values submittted via command builder
  @param uri the uri string
  @return the uri string after substitution