code: private void writeUnsafeStringLiteral(char value, StringBuilder out) {
      if (!isPrintable(value)) {
        // Don't emit non-Latin characters or control characters since they don't roundtrip well.
        out.append(String.format(value >= 0x100 ? "'\\u%04x'" : "'\\x%02x'", (int) value));
      } else {
        out.append('\'').append(escapeOutputString(String.valueOf(value))).append('\'');
      }
    }
docs: Appends a string literal which may not be printable with the given value onto the given buffer.