code: public List<PayloadType> getAudioPayloadTypesList() {
          ArrayList<PayloadType> result = new ArrayList<>();
          Iterator<PayloadType> jinglePtsIter = getPayloadTypes();
  
          while (jinglePtsIter.hasNext()) {
              PayloadType jpt = jinglePtsIter.next();
              if (jpt instanceof PayloadType.Audio) {
                  PayloadType.Audio jpta = (PayloadType.Audio) jpt;
                  result.add(jpta);
              }
          }
  
          return result;
      }
docs: Return the list of Payload types contained in the description.
  
  @return a list of PayloadType.Audio