sectionBuilder property Null safety

ExpandableSectionBuilder? sectionBuilder

use this return a custom content widget, when use this builder, headerBuilder is invalid. See also:

• github.com/tp7309/flutter_sticky_and_expandable_list/blob/master/example/lib/example_custom_section.dart, a description of what ExpandableSectionBuilder are and how to use it.

Implementation

ExpandableSectionBuilder? sectionBuilder;