9aab4a60f5
Prior to this commit the Spring Expression Language (SpEL) was able to properly parse an expression that uses the safe navigation operator (?.) with a method that has a `void` return type (for example, "myObject?.doSomething()"); however, SpEL was not able to evaluate or compile such expressions. This commit addresses the evaluation issue by selectively not boxing the exit type descriptor (for inclusion in the generated bytecode) when the method's return type is `void`. This commit addresses the compilation issue by pushing a null object reference onto the stack in the generated byte code when the method's return type is `void`. Closes gh-27421
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