Flutter 2 with null safity

[Bilal MurtaZa]

Hi, Bro I used this for a long time it's very helpful and time-saving.
but the problem is here dart release null safety and model changed in null safety.
please upgrade the dart JSON to a model with null safety.
thanks in advance.

[Rois Khoiron]

i ve same problem with format @required so manualy i fix it to 'required' only

[dharmikvyas]

I faced same issue. Please update dart JSON part. Many thanks.

[郭翰林]

可以看看我提交的PR，现在等待官方合并。#1904

[Nato Boram]

Duplicate of #1673