code: public void addArgument(String key, InputStream stream)
              throws JournalException {
          checkOpen();
          if (stream == null) {
              arguments.put(key, null);
          } else {
              try {
                  File tempFile = JournalHelper.copyToTempFile(stream);
                  arguments.put(key, tempFile);
              } catch (IOException e) {
                  throw new JournalException(e);
              }
          }
      }
docs: If handed an InputStream as an argument, copy it to a temp file and store
  that File in the arguments map instead. If the InputStream is null, store
  null in the arguments map.