Deprecate `DropdownButtonFormField` constuctor parameter `value` in favor of the parameter `initialValue`

The value parameter of the DropdownButtonFormField constructor was deprecated in favor of the initialValue parameter.

The value parameter of the DropdownButtonFormField constructor was used to initialize DropdownButtonFormField.initialValue. Not using the same name was confusing. For example, developers falsely assumed that setting value would change the current selected value. This was not the case—it only set the initial value or when the field is reset.

The value parameter of the DropdownButtonFormField constructor is deprecated in favor of the parameter named initialValue.

Replace the value parameter of the DropdownButtonFormField constructor with the initialValue parameter to initialize DropdownButtonFormField.initialValue.

Code before migration:

DropdownButtonFormField(
  value: 'Yellow',
),

Code after migration:

DropdownButtonFormField(
  initialValue: 'Yellow',
),

Landed in version: 3.33.0-1.0.pre
In stable release: TBD

API documentation:

• DropdownButtonFormField
• DropdownButtonFormField.initialValue

Relevant issues:

• Issue #169983

Relevant PRs:

• Deprecate DropdownButtonFormField value parameter in favor of initialValue