### Question:
ParameterUtils { public static String convertParameterPlaceholders(String parameterString, Map<String, String> parameterMap) { if (StringUtils.isEmpty(parameterString) || parameterMap == null) { return parameterString; } String cronTimeStr = parameterMap.get(Constants.PARAMETER_DATETIME); Date cronTime = null; if (StringUtils.isNotEmpty(cronTimeStr)) { cronTime = DateUtils.parse(cronTimeStr, Constants.PARAMETER_FORMAT_TIME); } else { cronTime = new Date(); } parameterString = PlaceholderUtils.replacePlaceholders(parameterString, parameterMap, true); if (cronTime != null) { parameterString = TimePlaceholderUtils.replacePlaceholders(parameterString, cronTime, true); } return parameterString; } private  ParameterUtils(); static String convertParameterPlaceholders(String parameterString, Map<String, String> parameterMap); static String convertParameterPlaceholders2(String parameterString, Map<String, String> parameterMap); static void setInParameter(int index, PreparedStatement stmt, DataType dataType, String value); static String curingGlobalParams(Map<String, String> globalParamMap, List<Property> globalParamList,
                                            CommandType commandType, Date scheduleTime); static String handleEscapes(String inputString); static String replaceScheduleTime(String text, Date scheduleTime); static Map<String, String> convert(Map<String, Property> paramsMap);  }### Answer:
@Test public void testConvertParameterPlaceholders() throws Exception { Assert.assertNull(ParameterUtils.convertParameterPlaceholders(null, null)); Map<String, String> parameterMap = new HashMap<String,String>(); parameterMap.put("testParameter","testParameter"); Assert.assertNull(ParameterUtils.convertParameterPlaceholders(null, parameterMap)); String parameterString = "test_parameter"; Assert.assertEquals(parameterString, ParameterUtils.convertParameterPlaceholders(parameterString, parameterMap)); parameterMap.put("testParameter2","${testParameter}"); Assert.assertEquals(parameterString,PlaceholderUtils.replacePlaceholders(parameterString, parameterMap, true)); Date cronTime = new Date(); Assert.assertEquals(parameterString, replacePlaceholders(parameterString, cronTime, true)); Date cronTimeStr = DateUtils.parseDate("20191220145900", new String[]{PARAMETER_FORMAT_TIME}); Assert.assertEquals(parameterString, replacePlaceholders(parameterString, cronTimeStr, true)); }