[rules-users] Usage of List in Drools 5.5.0

Created a Model in Guvnor 5.5.0 with 3 fields - 2 Text, 1 java.util.List The model is verified and validated - correctly. Source looks like below declare FormatConfig fieldName: String regEx: String regExPatterns: java.util.List end While trying to create a Business Rule using the above created Model. The rule gets fired and works fine. rule "MyFormat" dialect "mvel" when config : FormatConfig( fieldName == "AMOUNT" ) then config.setRegEx( "123" ); retract( config ); end But, the moment I try to use the List, by only declaring a List in the "When" section, the rule stops working. rule "MyFormat" dialect "mvel" when config : FormatConfig( fieldName == "AMOUNT" ) regExPatterns1: java.util.List ( ) then config.setRegEx( "123" ); retract( config ); end My final intention is to modify the regExPatterns list in the "THEN" block