clearComposing method Null safety
Set the composing region to an empty range.
The composing region is the range of text that is still being composed. Calling this function indicates that the user is done composing that region.
Calling this will notify all the listeners of this TextEditingController that they need to update (it calls notifyListeners). For this reason, this method should only be called between frames, e.g. in response to user actions, not during the build, layout, or paint phases.
Implementation
void clearComposing() {
value = value.copyWith(composing: TextRange.empty);
}