How to make Jackson to avoid excaping backslash?

Create declare mapper:
private static final ObjectMapper mapper = new ObjectMapper(new ObjectMapper().getFactory().setCharacterEscapes(new CharacterEscapes() {
    @Override
    public int[] getEscapeCodesForAscii() {
      // add standard set of escaping characters
      int[] esc = CharacterEscapes.standardAsciiEscapesForJSON();
      // don't escape backslash (not to corrupt windows path)
      esc['\\'] = CharacterEscapes.ESCAPE_NONE;
      return esc;
    }

    @Override
    public SerializableString getEscapeSequence(int i) {
      // no further escaping (beyond ASCII chars) needed
      return null;
    }
  })).enable(INDENT_OUTPUT);

Usage:

mapper.writeValueAsString(configMap)