SysExtensionSerializerFormRunHelper

Out of the box table extension framework can not get child table from form if it is delayed joined.
SysExtensionSerializerFormRunHelper is a class helper which should resolve this issue.
It's implementation on form is quite easy:
1. Add declaration to classDeclaration:

SysExtensionSerializerFormRunHelper formRunHelper;

2. Additional method at element level:

public SysExtensionSerializerFormRunHelper formRunHelper()
{
    if (!formRunHelper)
    {
        formRunHelper = SysExtensionSerializerFormRunHelper::construct();
    }

    return formRunHelper;
}

3. Modify init method of child DataSource and add following line after super():

element.formRunHelper().addExtensionTablePair(ParentTable, ChildTableExtension);

That's all, good to go!
Example can be found at MCROrderDetail form.

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