}

    public void test_appendLineNumber() {
        DocumentHelper documentHelper = new DocumentHelper();

        assertEquals("", documentHelper.appendLineNumber("L", null));
        assertEquals("", documentHelper.appendLineNumber("L", ""));
        assertEquals("", documentHelper.appendLineNumber("L", " "));
        assertEquals("", documentHelper.appendLineNumber("L", "\n"));

            } catch (final IOException e) {
                logger.warn("Failed to encode {}", hash, e);
            }
        }
        return hash;
    }

    public String appendLineNumber(final String prefix, final String content) {
        if (StringUtil.isBlank(content)) {
            return StringUtil.EMPTY;
        }
        final String[] values = content.split("\n");