Majority vote operator does not work in mining model

Majority vote operator does not work in new PMML implementation. Evaluation fails with the following exception:

java.lang.NullPointerException
at org.drools.core.rule.constraint.MvelConstraint.equals(MvelConstraint.java:675)
at org.drools.core.reteoo.AlphaNode.equals(AlphaNode.java:198)
at java.base/java.util.HashMap.getNode(HashMap.java:567)
at java.base/java.util.HashMap.get(HashMap.java:552)
at org.drools.core.reteoo.CompositeObjectSinkAdapter.getMatchingNode(CompositeObjectSinkAdapter.java:523)
at org.drools.core.reteoo.builder.BuildUtils.attachNode(BuildUtils.java:117)