code: protected ObjectMapper configure(ObjectMapper mapper) {
          mapper.configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true);
          mapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);
  
          return mapper;
      }
docs: configures given object mapper instance.
  
  @param mapper the object to configure
  @return mapper instance for chaining