Simplest configuration:

      <valueSelector/>

Advanced configuration:

      <valueSelector>
        ... <!-- Normal selector properties -->
        <variableName>room</variableName>
      </valueSelector>

The variableName property is only required if it cannot be deduced automatically because there are multiple variables (for the related entity class).

In exotic Construction Heuristic configurations, the entityClass from the EntitySelector sometimes needs to be downcasted, which can be done with the property downcastEntityClass:

      <valueSelector>
        <downcastEntityClass>...LeadingExam</downcastEntityClass>
        <variableName>period</variableName>
      </valueSelector>

If a selected entity cannot be downcasted, the ValueSelector is empty for that entity.