private ResponseMapper upperCaseResponseMapper() {
    return (response, type) -> {
      try {
        return response.toBuilder()
            .body(Util.toString(response.body().asReader()).toUpperCase().getBytes())
            .build();
      } catch (final IOException e) {
        throw new RuntimeException(e);
      }
    };
  }
The type of a parameter value may not be the desired type to encode as. Prefer the interface
type.
hc5/src/test/java/feign/hc5/AsyncApacheHttp5ClientTest.java