BUG: in UML 2.5, isSubstituable:Boolean[0..1] = true there should be 3 values: None, Some(true), Some(false) but the MD API only gives 2: true, false
BUG: in UML 2.5, isSubstituable:Boolean[0..1] = true there should be 3 values: None, Some(true), Some(false) but the MD API only gives 2: true, false