deepMerge method
Deep merges this map with other and returns a new map.
When both maps contain a nested map for the same key, those maps are
merged recursively. Otherwise, the value from other overwrites this one.
Implementation
Map<String, Object?> deepMerge(Map<String, Object?> other) {
final base = _toObjectMapFromEntries(entries);
return _deepMergeMaps(base, other);
}