Question about not() behaviour with null values

[Totremont]

I have an entity with a Boolean attribute memoryStored that can accept: true, false or null.
I wanted to fetch every row that does not have memoryStored equal true so I added this line :

query.addConstraint(ConstraintBuilder.of("memoryStored").equal(true).not());
I expect this to target both false and null values.

However, I am only getting the rows with false. Null values are not being retrieved.
Is there something I am not doing right or is this a bug ?

[javier-godoy]

Query spec semantics is based on three-valued logic (think of "NULL" as "UNKNOWN", i.e. it's not possible to know the truth value).

• Any comparison operator involving an UNKNOWN operand yields the truth value UNKNOWN.
• Negating UNKNOWN is still UNKNOWN: Applying a logical NOT to an UNKNOWN state does not magically create certainty. If you lack the data to know if a statement is true, you inherently lack the data to declare it false. Therefore, NOT (UNKNOWN) evaluates to UNKNOWN

[javier-godoy]

I expect this to target both false and null values.

Such a constraint would be (memoryStored <> true OR memoryStored is NULL), but support for OR constraints (#61) is currently available from 1.2.0-SNAPSHOT only.