Prior to this commit the SpEL compiler would generate bad bytecode
if the left hand operand of an instanceof was a primitive or
if the right hand operand was a primitive type reference.
With the fixes primitives on the left hand side are now
correctly boxed and special handling is in place for when the
right hand side is a primitive type reference. Using a primitive
type reference on the right always causes the instanceof
check to return false.
Additionally a guard has been added such that compilation is
not allowed when the right hand side of an expression
is not a type reference. If it is, for example, a variable
reference that evaluates to a type reference then that
cannot be expressed in bytecode so compilation is not performed.
Issue: SPR-14250
a31f0bb3c0