code: public static Contract load(File idlJson) throws IOException {
          FileInputStream fis = new FileInputStream(idlJson);
          Contract c = load(fis);
          fis.close();
          return c;
      }
docs: Loads the IDL JSON file, parses it, and returns a Contract.
  Uses the JacksonSerializer.
  
  @param idlJson Barrister IDL JSON file to load
  @return Contract based on the IDL JSON file
  @throws IOException If there is a problem reading the file, or if JSON
  deserialization fails