mergeIfMissing method
Implementation
void mergeIfMissing(Map<String, dynamic> values) {
final view = _all;
var changed = false;
for (final entry in values.entries) {
if (!view.containsKey(entry.key)) {
body[entry.key] = entry.value;
view[entry.key] = entry.value;
changed = true;
}
}
if (changed) _allData = view;
}