apollo-openapi/src/main/java/com/ctrip/framework/apollo/openapi/client/url/OpenApiPathBuilder.java/OpenApiPathBuilder/addParam
class OpenApiPathBuilder:  public OpenApiPathBuilder addParam(String key, Object value) {
    if (Strings.isNullOrEmpty(key)) {
      throw new IllegalArgumentException("Param key should not be null or empty");
    }
    this.params.put(key, escapeParam(String.valueOf(value)));
    return this;
  }