Android Room getting count of elements in an 'incoming foreign key list' in an 'embedded entity'?

I have 2 Entities, Grade and Student, Student is having a foreign key towards the class room. Embedded entity ClassRoom looks like this,

data class ClassRoom(

    @Embedded
    val level: ClassLevel

    @Relation(
        parentColumn = "id",
        entityColumn = "ClassLevel"
    )
    val students: List<Student>,

    // val strength: Int ?

) 

What I am trying to achieve is, using ClassRoomInstance.strength to get the count of incoming foreign keys. Than calculating the sizes of students with students.size

What is the way to achieve this?

Thanks

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