code: public void addFile(File file, String name) {
          files.put(name, file);
  
          // remove duplicate key
          if (fileStreams.containsKey(name)) {
              fileStreams.remove(name);
          }
      }
docs: Adds a file to your assembly. If the field name specified already exists, it will override the content of the
  existing name.
  
  @param file {@link File} the file to be uploaded.
  @param name {@link String} the field name of the file when submitted Transloadit.