[rules-users] rule parse error for null check

Hi,I'm using drools-5.3.0.Beta1. I've following rule file: import java.util.*; declare Student    name : String @key    subjectGradeMap : HashMap    end   rule "Subject grade points" dialect "mvel" when    $u : Student() then    if($u.subjectGradeMap == null)    {       $u.subjectGradeMap = new HashMap<String,Integer>();    }    $u.subjectGradeMap["CompSc"] += 100;    System.out.println("Marks added"); end I get following error while rule compilation:Unable to Analyse Expression if($u.subjectGradeMap == null);    {       $u.subjectGradeMap = new HashMap<String,Integer>();    };    $u.subjectGradeMap["CompSc"] += 100;    System.out.println("Marks added");: [Error: was expecting type: java.lang.Object; but found type: <Unknown>] [Near : {... if($u.subjectGradeMap == null) ....}]              ^ [Line: 1, Column: 1] : [Rule name='Subject grade points'] Please let me know if this is correct usage in the above scenario. Thanks,Neel