Specification clearly states that isXXX() accessor is allowed only for boolean primitive, but is not permissible for Boolean object. The reason for that shows nicely for example in MAGNOLIA-5028. Seeing isXXX() developers tend to assume that method would always return just true or false value, while in fact it can return also null.
We need to deprecate all such Boolean isXXX() methods and replace them with Boolean getXXX and also fix their usage in our code as there might be other similar bugs like in MAGNOLIA-5028.