Set a high threshold value for hashing, either using the API:
RuleBaseConfiguration conf = new RuleBaseConfiguration();
conf.setAlphaNodeHashingThreshold( 999 );
RuleBase base = RuleBaseFactory.newRuleBase( conf );
Or by setting the system property:
drools.alphaNodeHashingThreshold = 999
Description
Alpha hashing is incorrect calculating hash codes for character attributes.