Method security annotations, like PreAuthorize, not working on private methods after upgrade to 6.4

[betalb]

Describe the bug
Method security annotations, like PreAuthorize, not working on private methods after upgrade to spring-security 6.4. This only works in case of AspectJ compile time weaving (probably load time should work too, but I was not able to create workable example).

Those annotations worked in spring-security 6.3 and earlier.
I see that there was some refactoring in annotation processing code, and it seems that linked method is explicitly rejecting private class members:

spring-security/core/src/main/java/org/springframework/security/core/annotation/UniqueSecurityAnnotationScanner.java

Line 228 in 79bacf8

return (!Modifier.isPrivate(candidateMethod.getModifiers())

To Reproduce
Create project that has dependency on spring-security-aspects, aspectjrt and uses aspectj-maven-plugin for compile-time weaving.

Create Rest endpoint that has PreAuthorize annotation on private method

@RestController
@RequestMapping(produces = MediaType.APPLICATION_JSON_VALUE)
public class Endpoint {

    @GetMapping
    public List<String> get() {
        return doGet();
    }

    @PreAuthorize("denyAll()")
    private List<String> doGet() {
        return List.of("nothing");
    }

}

Expected behavior
User should see 403 error, but instead he sees a response ["nothing"]

Sample

self-invocation.zip

In attached sample if modifier is changed from private to protected on method name.vitalii.selfinvocation.Endpoint#doGet, app starts to work as expected.

[betalb]

I tried to briefly check spring-core AnnotationsScanner and it looks like it allowed private methods, but only if method being called is defined on targetClass and not on parent classes. And it seems that sping-security version has check for this case

spring-security/core/src/main/java/org/springframework/security/core/annotation/UniqueSecurityAnnotationScanner.java

Line 217 in 79bacf8

if (candidate == method) {

but it breaks in scenario of aspectj compilation.