optaplanner-core/src/main/java/org/optaplanner/core/impl/domain/variable/descriptor/GenuineVariableDescriptor.java
public boolean isInitialized(Object entity) {
        if (nullable) {
            return true;
        }
        Object variable = getValue(entity);
        return variable != null;
    }
public boolean isInitialized(Object entity) {
        if (nullable) {
            return true;
        }
        Object variable = getValue(entity);
        return variable != null;
    }
A {@link PlanningVariable#nullable()} value is always considered initialized, but it can still be reinitialized
with {@link PlanningVariable#reinitializeVariableEntityFilter()}.
@param entity never null
@return true if the variable on that entity is initialized