code: public static DesignDocument fromFile(File file) throws FileNotFoundException {
          assertNotEmpty(file, "Design js file");
          DesignDocument designDocument;
          Gson gson = new Gson();
          InputStreamReader reader = null;
          try {
              reader = new InputStreamReader(new FileInputStream(file),"UTF-8");
              //Deserialize JS file contents into DesignDocument object
              designDocument = gson.fromJson(reader, DesignDocument.class);
              return designDocument;
          } catch (UnsupportedEncodingException e) {
              //UTF-8 should be supported on all JVMs
              throw new RuntimeException(e);
          } finally {
              IOUtils.closeQuietly(reader);
          }
      }
docs: Deserialize a javascript design document file to a DesignDocument object.
  
  @param file the design document javascript file (UTF-8 encoded)
  @return {@link DesignDocument}
  @throws FileNotFoundException if the file does not exist or cannot be read