docs: public static String interpolate(File dockerFile, FixedStringSearchInterpolator interpolator) throws IOException {
          StringBuilder ret = new StringBuilder();
          try (BufferedReader reader = new BufferedReader(new FileReader(dockerFile))) {
              String line;
              while ((line = reader.readLine()) != null) {
                  ret.append(interpolator.interpolate(line)).append(System.lineSeparator());
              }
          }
          return ret.toString();
      }