我在Optaplanner中有以下Drools规则：

rule "oneShiftPerDay"
when
    $leftAssignment : ShiftAssignment($leftId : id, $employee : employee, $shiftDate : shiftDate, employee != null)
    $rightAssignment : ShiftAssignment(employee == $employee, shiftDate == $shiftDate, id > $leftId)
then
    scoreHolder.addHardConstraintMatch(kcontext, -1); end

但是当我运行求解器时，我得到以下错误：

09:02:46.128 [main] ERROR o.d.c.k.b.impl.AbstractKieModule - Unable to build     KieBaseModel:defaultKieBase Error                      importing : 'be.comp.permanenties.domain.solver.EmployeeAssignmentTotal'
Error importing : 'be.comp.permanenties.domain.solver.EmployeeWorkSequence'
Rule Compilation error : [Rule name='oneShiftPerDay']
        be/comp/permanenties/solver/Rule_oneShiftPerDay544009415.java (2:220) : Only a type can be imported. be.comp.permanenties.domain.solver.EmployeeWorkSequence resolves to a package
        be/comp/permanenties/solver/Rule_oneShiftPerDay544009415.java (2:978) : Only a type can be imported. be.comp.permanenties.domain.solver.EmployeeAssignmentTotal resolves to a package

我如何解决这个错误？谢谢。

亲切的问候，

尼克