Simple Select-Dropdown for a NavigationProperty

Question

For a current project, we're using Olingo in backend for OData v4 data access and openui5 as frontend framework. We know, that odata v4 is in a more experimental state in openui5 but we're doing not so bad with it. As it is normal for us, to use a workaround here and there, we're struggeling with following problem right now where I think there should be a really simple way instead of building a workaround.

Simplified oData v4 Model:

<EntityType Name="Notification">
  <Key>
    <PropertyRef Name="uid"/>
  </Key>
  <Property Name="uid" Type="Edm.Int32"/>
  <Property Name="recievedAt" Type="Edm.Date"/>
  <NavigationProperty Name="NotificationType" Type="rest.odata.BaseData" Nullable="false"/>
</EntityType>

<EntityType Name="BaseData">
  <Key>
    <PropertyRef Name="key"/>
  </Key>
  <Property Name="key" Type="Edm.String"/>
  <Property Name="title" Type="Edm.String"/>
</EntityType>

The BaseData-Entity is used for different key-value-lists - in this case for a NotificationType. We have couple of types summarized and represented in an EntitySet:

<EntitySet Name="basedataNOTIFICATIONTYPES" EntityType="rest.odata.BaseData"/>

Now we're struggeling in the frontend with a simple sap.m.Select-Dropdown which should define the NotificationType of our Notification.

The Select-Control is defined like this:

var oControl = new sap.m.Select(sName, {selectedKey: "{NotificationType/key}"});
oControl.bindItems({
  path: "/basedataNOTIFICATIONTYPES"
})

(I simplified the code very much)

The parent form is binded to a specific /Notification context.

This is what happens: The Select-Dropdown shows the current saved NotificationType of our specific /Notification. If I select another NotificationType from the dropdown, ui5 sends a PATCH Request to the EntitySet /basedataNOTIFICATIONTYPES. This is not the behaviour I expected. I need a PATCH Request sent to the specific /Notification(XXX)/NotificationType/key to update it.

Has anyone a hint for me?

Thanks in advance! :-)