Compilation failure using null safe dereferencing and memberOf together ----------------------------------------------------------------------- Key: DROOLS-50 URL: https://issues.jboss.org/browse/DROOLS-50 Project: Drools Issue Type: Bug Security Level: Public(Everyone can see) Reporter: Mario Fusco Assignee: Mario Fusco Fix For: 5.6, 6.0.0.Alpha1 Having a pattern like: {code} Attribute( this memberOf $atts || this memberOf $seq!.particle ) {code} where $atts is bound to a list property and $seq.particle is also a list property. $seq may be null, hence the !. accessor, the compiler produces the following failure Unable to Analyse Expression $atts contains this || $seq.particle contains $seq != null && this