code: public byte[] readPDU(DataInputStream in, int commandLength, int commandId,
              int commandStatus, int sequenceNumber) throws IOException {
          synchronized (in) {
              return pduReader.readPDU(in, commandLength, commandId,
                      commandStatus, sequenceNumber);
          }
      }
docs: /*
  (non-Javadoc)
  
  @see org.jsmpp.PDUReader#readPDU(java.io.InputStream, int, int,
  int, int)