code: String buildDirectoryContentIndent(String indent) {
  
      return Optional.ofNullable(indent).filter(StringUtils::hasText)
        .map(it -> it + StringUtils.SINGLE_SPACE + SUB_DIRECTORY_OFFSET + DIRECTORY_SWIM_LANE)
        .orElseGet(() ->StringUtils.SINGLE_SPACE + DIRECTORY_SWIM_LANE);
    }
docs: /* (non-Javadoc)