I migrated a set of rules from version 5.4 to 6.3. All rules are "Technical rules".
After migration, I get the following error

_Unable to Analyse Expression value != 0: [Error: Comparison operation requires compatible types. Found class org.mvel2.util.MethodStub and class java.lang.Integer] [Near :

] ^ [Line: 29, Column: 9]
_

on the following line of a rule

$imponibile : RuleElement(label=="IMPONIBILE", value != 0, imponibile : value, imponibile_artmap : artmap);

RuleElement is a model class (loaded as a dependency) and declares a value attribute like

private Double value;

The same rule compiled without problems in 5.4.

Thanks