In non-executable model, when I assign an integer value to a BigDecimal-type variable, the type of the variable changes to Integer unexpectedly.

Issue

In non executable model, when I build a maven project containing rules like (*1), maven build fails with a ClassCastException like (*e1).
Specifically, when I assign an integer value to BigDecimal-type variable $value1 at line (*1-1), the ClassCastException (*e1) occurs at subsequent addition expression at line (*1-2).

(*1) Example rule

dialect "mvel"


rule "Rule 1"
    when
        $fact : Fact()
    then
        $value1 = $fact.value1;
        $value2 = $fact.value2;

        $value1 = 5;                   // <---------- (*1-1)

        $total = $value1 + $value2;    // <---------- (*1-2)

        System.out.println("$total = " + $total);
end
// Fact#value1 and Fact#value2 are both BigDecimal-type properties.

(*e1) Exception

Exception executing consequence for rule "Rule 1" in com.example.reproducer: java.lang.ClassCastException: class java.lang.Integer cannot be cast to class java.math.BigDecimal (java.lang.Integer and java.math.BigDecimal are in module java.base of loader 'bootstrap')
    at org.drools.core.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)
    at org.drools.core.common.DefaultAgenda.handleException(DefaultAgenda.java:1056)
    at org.drools.core.phreak.RuleExecutor.innerFireActivation(RuleExecutor.java:462)
    at org.drools.core.phreak.RuleExecutor.fireActivation(RuleExecutor.java:402)
    at org.drools.core.phreak.RuleExecutor.fire(RuleExecutor.java:158)
    at org.drools.core.phreak.RuleExecutor.evaluateNetworkAndFire(RuleExecutor.java:110)
    at org.drools.core.concurrent.AbstractRuleEvaluator.internalEvaluateAndFire(AbstractRuleEvaluator.java:33)
    at org.drools.core.concurrent.SequentialRuleEvaluator.evaluateAndFire(SequentialRuleEvaluator.java:43)
    at org.drools.core.common.DefaultAgenda.fireLoop(DefaultAgenda.java:869)
    at org.drools.core.common.DefaultAgenda.internalFireAllRules(DefaultAgenda.java:816)
    at org.drools.core.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:808)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.internalFireAllRules(StatefulKnowledgeSessionImpl.java:1341)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1332)
    at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:1316)
    at com.example.reproducer.DroolsTest.main(DroolsTest.java:25)
Caused by: java.lang.ClassCastException: class java.lang.Integer cannot be cast to class java.math.BigDecimal (java.lang.Integer and java.math.BigDecimal are in module java.base of loader 'bootstrap')
    at org.mvel2.math.MathProcessor.doOperations(MathProcessor.java:65)
    at org.mvel2.ast.BinaryOperation.getReducedValueAccelerated(BinaryOperation.java:146)
    at org.mvel2.compiler.ExecutableAccessor.getValue(ExecutableAccessor.java:38)
    at org.mvel2.ast.AssignmentNode.getReducedValueAccelerated(AssignmentNode.java:116)
    at org.mvel2.MVELRuntime.execute(MVELRuntime.java:85)
    at org.mvel2.compiler.CompiledExpression.getDirectValue(CompiledExpression.java:115)
    at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:111)
    at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:105)
    at org.mvel2.MVEL.executeExpression(MVEL.java:946)
    at org.kie.soup.project.datamodel.commons.util.RawMVELEvaluator.executeExpression(RawMVELEvaluator.java:103)
    at org.drools.mvel.expr.MvelEvaluator.internalEvaluate(MvelEvaluator.java:131)
    at org.drools.mvel.expr.MvelEvaluator.evaluate(MvelEvaluator.java:115)
    at org.drools.mvel.expr.MVELConsequence.evaluate(MVELConsequence.java:94)
    at org.drools.core.phreak.RuleExecutor.innerFireActivation(RuleExecutor.java:455)
    ... 12 more