docs: public PayloadBuilder resizeAlertBody(final int payloadLength, final String postfix) {
          int currLength = length();
          if (currLength <= payloadLength) {
              return this;
          }
  
          // now we are sure that truncation is required
          String body = (String)customAlert.get("body");
  
          final int acceptableSize = Utilities.toUTF8Bytes(body).length
                  - (currLength - payloadLength
                          + Utilities.toUTF8Bytes(postfix).length);
          body = Utilities.truncateWhenUTF8(body, acceptableSize) + postfix;
  
          // set it back
          customAlert.put("body", body);
  
          // calculate the length again
          currLength = length();
  
          if(currLength > payloadLength) {
              // string is still too long, just remove the body as the body is
              // anyway not the cause OR the postfix might be too long
              customAlert.remove("body");
          }
  
          return this;
      }