ConcurrentModificationException error when retracting fact in a for loop

Issue

when retracting fact in a for loop like below:

package com.sample

import java.util.List;

rule "Test"
    when
        $list : List(size == 3) from collect(String())
    then
        System.out.println("Fired rule: Test");
        for (Object fact : $list) {
            System.out.println("Retracting fact");
            retract(fact);
        }
end

If insert three strings, fire rule get ConcurrentModificationException.

Caused by: java.util.ConcurrentModificationException
    at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
    at java.util.AbstractList$Itr.next(AbstractList.java:343)
    at com.sample.Rule_Test_f9c1ba5d160c4560b80b951b05b30ba5.defaultConsequence(Rule_Test_f9c1ba5d160c4560b80b951b05b30ba5.java:8)
    at com.sample.Rule_Test_f9c1ba5d160c4560b80b951b05b30ba5DefaultConsequenceInvoker.evaluate(Unknown Source)
    at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1204)
    ... 6 more