docs: private String toStringFormChangedPropertiesMap(Map<String, String> delta) {
          if (delta == null || delta.isEmpty()) {
              return "";
          }
          StringBuffer sb = new StringBuffer();
          for (Map.Entry<String, String> entry : delta.entrySet()) {
              if (sb.length() > 0) {
                  sb.append(",");
              }
              sb.append(entry.getKey()).append("=").append(entry.getValue());
          }
          return sb.toString();
      }