When using Chinese input methods, the text field cannot line feed，but English input methods can work.

1. use a TextFormFiled widget:

TextFormField(
       maxLines: 5,
       keyboardType: TextInputType.multiline,
       textInputAction: TextInputAction.newline
)

2. Keyboard use Chinese input methods, press the newline key, it can't work.
3. Keyboard use English input methods, press the newline key, work well.