code: protected String getKey(String hostName, String contextPath) {
          return String.format("%s/%s", (hostName == null ? EMPTY : hostName), (contextPath == null ? EMPTY : contextPath));
      }
docs: Return scope key. Scope key consists of host name concatenated with context path by slash symbol
  
  @param hostName
  Host name
  @param contextPath
  Context path
  @return Scope key as string