initialHeaderBuild property
If builder should render header during first run
To perform accurate header build, by default it renders after first paint is finished, when headerStateBuilder is defined.
In some cases it can lead to header render delay.
To prevent this you can set initialHeaderBuild to true.
In that case header will be rendered during initial render with basic StickyState object.
It will add additional header renderer call.
If this value is false - header render callback will be called
only after it's parent and content will be laid out.
For case when only headerBuilder is defined, this property will be ignored
If it's relative header positioning (InfiniteListItem.overlay constructor is used),
this property always will be true, which means that with relative
positioning, header will be built with basic StickyState object.
It's required due to layout container and define it's actual dimensions
Implementation
final bool initialHeaderBuild;