protected String encode(Object value) {
      return UriUtils.encode(value.toString(), Util.UTF_8);
    }
Expression that adheres to Simple String Expansion as outlined in <a
href="https://tools.ietf.org/html/rfc6570#section-3.2.2>Simple String Expansion (Level 1)</a>
core/src/main/java/feign/template/Expressions.java