Separate list items by whitespace and higher level metrics by tabs

I have the following functions:

 public String tabSerializer(String log, String time) {
        StringJoiner joiner = new StringJoiner("\t");
        addValue(company, joiner);
        addValue(users, joiner);
        ...
        return joiner.toString();
     }


  private static void addValue(Object value, StringJoiner joiner){
        if(value instanceof List){
            addValuesFromList((List<?>)value, joiner);
        }
        else{
            joiner.add(String.valueOf(value));
        }
    }
  private static void addValuesFromList(List<?> arr, StringJoiner joiner) {
        for(int i=0; i<arr.size(); i++){
            Object value = arr.get(i);
            addValue(value, joiner);
        }
    }

company is a List of strings. Example: [Apple, mango]. I am trying to separate all the values passed in tabSerializer() function by a tab. However, using my current code, I am getting tabs even between list values (eg, apple mango) instead of whitespace.

I want to separate list values by whitespaces while still separate all higher level dimesnions by tabs.

I tried adding: value= value + " " in the "addValuesFromList()" function but don't know how to further use that to integrate with the joiner.

Any help would be appreciated.

Or if you still want to use StringJoiner use second joiner in addValuesFromList.

private static void addValuesFromList(List<?> arr, StringJoiner joiner) {
    StringJoiner spaceJoiner = new StringJoiner(" ");

    for (int i = 0; i < arr.size(); i++) {
        Object value = arr.get(i);
        spaceJoiner.add(String.valueOf(value));
    }
    String spacedValue = spaceJoiner.toString(); 
    addValue(spacedValue, joiner);

}

will it do what you need?