about IComponentConnector2 - winrt-xaml

Question

I have the following code
struct MainPage : PageT<MainPage,IComponentConnector,IComponentConnector2>
{...}
How GetBindingConnector get called? As a comparison, I know if I set the ConnectionId attribute on the Xaml page, IComponentConnector.Connect will get called. So there must exist some attribute(s) that will trigger GetBindingConnector, then what's that? Many thanks!!!
<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Button Content="Test" x:ConnectionId="1"/>
</Page>
New Update
1,Using x:Bind and GetBindingConnector called
<Page
x:Class="BlankApp1.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:BlankApp1"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Button x:Name="myButton" Content="{x:Bind MyProperty}"/>
</Page>
and the dump of xbf
PushScopeAddNamespace (prefix=(null), namespace=http://schemas.microsoft.com/winfx/2006/xaml/presentation)
AddNamespace (prefix=x, namespace=http://schemas.microsoft.com/winfx/2006/xaml)
AddNamespace (prefix=local, namespace=using:BlankApp1)
AddNamespace (prefix=d, namespace=http://schemas.microsoft.com/expression/blend/2008)
AddNamespace (prefix=mc, namespace=http://schemas.openxmlformats.org/markup-compatibility/2006)
CreateTypeBeginInit (type=Windows.UI.Xaml.Controls.Page)
SetConnectionId (Id=type=Signed, value=1)
CheckPeerType (x:Class=BlankApp1.MainPage)
PushScopeCreateTypeBeginInit (type=Windows.UI.Xaml.Controls.Button)
SetConnectionId (Id=type=Signed, value=2)
SetName (x:Name=myButton)
EndInitPopScope
SetValue (property=Windows.UI.Xaml.Controls.UserControl.Content)
EndInitPopScope
2, Not using x:Bind:
<Page
x:Class="BlankApp1.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="using:BlankApp1"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d">
<Button x:Name="myButton"/>
</Page>
and the dump of xbf
PushScopeAddNamespace (prefix=(null), namespace=http://schemas.microsoft.com/winfx/2006/xaml/presentation)
AddNamespace (prefix=x, namespace=http://schemas.microsoft.com/winfx/2006/xaml)
AddNamespace (prefix=local, namespace=using:BlankApp1)
AddNamespace (prefix=d, namespace=http://schemas.microsoft.com/expression/blend/2008)
AddNamespace (prefix=mc, namespace=http://schemas.openxmlformats.org/markup-compatibility/2006)
CheckPeerType (x:Class=BlankApp1.MainPage)
CreateTypeBeginInit (type=Windows.UI.Xaml.Controls.Page)
PushScopeCreateTypeBeginInit (type=Windows.UI.Xaml.Controls.Button)
SetConnectionId (Id=type=Signed, value=2)
SetName (x:Name=myButton)
EndInitPopScope
SetValue (property=Windows.UI.Xaml.Controls.UserControl.Content)
EndInitPopScope
3, differences of the 2 dumps
I'm not sure if this is the root cause that makes difference.