code: private String acceptBuilder(String version) {
          String acceptValue = "application/json";
          if(version == "2.1") acceptValue += ";version=" + version;
  
          return acceptValue;
      }
docs: This method is used to validate and build the accept JSON version.
  
  @param   version
  {@code String} version
  
  @return  {@code String} the mounted header value