Spring Framework 5.1.8 introduced a regression for the compilation of
SpEL expressions referencing a method declared in an interface. An
attempt to compile such an expression resulted in a
SpelEvaluationException caused by an IncompatibleClassChangeError.
This commit fixes this regression by adding explicit support in
ReflectivePropertyAccessor.OptimalPropertyAccessor.generateCode() for
methods declared in interfaces.
Closes gh-24357
da02b7a141