This question is not seeking a solution. But an explanation for the working solution.

The problem I had was to create a nested JSON where I get the hierarchy in a dot(.) separated formate.

example

Path: a.b.c.d
Value: 123

output should be

{
    "A": {
        "B": {
            "C": {
                "D": 123
            }
        }
    }
}

Now I do have a working solution for this

import 'dart:convert';

Map<String, dynamic> mainJson = {};

void main() {
  List<String> references = [
    'A.B.C.D1',
    'A.B1.C.D1',
    'A.B2.C.D3',
  ];
  for (var reference in references) {
    enterValueForReference(reference, '123');
  }
  print(jsonEncode(mainJson));
}

enterValueForReference(String reference, dynamic value) {
  List<String> nodes = reference.split(".").toList();
  List<String> parentNodes = nodes.sublist(0, nodes.length - 1);
  Map<String, dynamic> parentJson = {};
  Map<String, dynamic> lastJson = {nodes.last: value};
  parentJson = mainJson;
  for (var node in parentNodes) {
    if (parentJson.keys.contains(node) == false) {
      parentJson[node] = Map<String, dynamic>();
    }
    parentJson = parentJson[node];
  }
  parentJson.addAll(lastJson);
}

I just don’t know how this is working. parentJson = mainJson; this creates a reference between parentJson and mainJson but, parentJson = parentJson[node]; this should update the mainJson as well, right?

If anyone can make sense of the code, that would be helpful.