code: private String parameterToString(Object param) {
          if (param == null) {
              return "";
          } else if (param instanceof Date) {
              return formatDate((Date) param);
          } else if (param instanceof Collection) {
              StringBuilder b = new StringBuilder();
              for (Object o : (Collection) param) {
                  if (b.length() > 0) {
                      b.append(",");
                  }
                  b.append(String.valueOf(o));
              }
              return b.toString();
          } else {
              return String.valueOf(param);
          }
      }
docs: Format the given parameter object into string.