Hi everyone, I've tried to go from Drools 5.3.0.Final to 5.4.0.Final and some strange errors appeared on constraints using the size of a list. For instance, given the following object: public class MyObject { private List<String> param = new ArrayList<String>(); public MyObject() { super(); } public List<String> getParam() { return param; } public void setParam(List<String> param) { this.param = param; } } This rule: rule "Sample rule" when MyObject( param.size > 0 ) then System.out.println( "Sample rule activated" ); end Provokes the following error: Unable to Analyse Expression param.size > 0: [Error: Comparison operation requires compatible types. Found class java.lang.String and class java.lang.Integer] [Near : {... param.size > 0 ....}] ^ : [Rule name='Sample rule'] This worked very well in Drools 5.3.0.Final. Is there some configuration specific to Drools 5.4.0.Final that I've missed in the release notes? Thanks in advance for your help. Best, Alexis