code: public void setProcessInputStream(OutputStream os) {
          if (input != null) {
              inputThread = createPump(input, os, true, nonBlockingRead);
          } else {
              try {
                  os.close();
              } catch (IOException e) {
                  //ignore
              }
          }
      }
docs: Set the <code>OutputStream</code> by means of which
  input can be sent to the process.
  
  @param os the <code>OutputStream</code>.