code: @Nonnull
      public JsonToken expectString(String message) throws IOException, JsonException {
          if (!hasNext()) {
              throw newParseException("Expected %s (string literal): Got end of file", message);
          } else {
              if (unreadToken.isLiteral()) {
                  JsonToken tmp = unreadToken;
                  unreadToken = null;
                  return tmp;
              }
  
              throw newMismatchException("Expected %s (string literal): but found '%s'",
                                         message, unreadToken.asString());
          }
      }
docs: Expect a string literal JSON token. A string literal is a double-quote
  delimited UTF-8 encoded, JSON-escaped string.
  
  @param message Message to add to exception if there are no more JSON
  tokens on the stream.
  @return The string literal token.
  @throws JsonException If no more tokens, or the token is illegally
  formatted.
  @throws IOException If unable to read from stream.