code: private void buildDirectives(PatternCacheControl patternCacheControl) {
          for (Map.Entry<Directive, String> entry : patternCacheControl.getDirectives().entrySet()) {
              Directive key = entry.getKey();
              String value = entry.getValue();
  
              switch (key) {
              case MAX_AGE:
              case MAX_AGE_MPLUS:
                  maxAgeDirectives.put(key, value);
                  break;
              default:
                  if (value.equals(EMPTY_STRING_VALUE)) {
                      staticDirectives.append(key.getName() + DIRECTIVES_SEPARATOR);
                      break;
                  }
                  staticDirectives.append(key.getName() + EQUALS_STRING + value + DIRECTIVES_SEPARATOR);
              }
          }
      }
docs: Builds a string of directives by concatenating all the static directives
  @param patternCacheControl