Allow authenticationManagerResolver to take precedence over jwt/opaqueToken

[academey]

When OAuth2ResourceServerConfigurer.authenticationManagerResolver() is configured, it now takes precedence over any jwt() or opaqueToken() configuration without throwing an exception. This follows Spring Security's convention where specialized configurations take precedence over general ones at runtime.

Problem

The current implementation throws an exception when authenticationManagerResolver() is used together with jwt() or opaqueToken() configurations. This prevents legitimate use cases such as Spring Authorization Server needing to support both JWT and opaque tokens dynamically.

Solution

The solution removes the validation check that prevented authenticationManagerResolver from being used with jwt/opaqueToken configurations. The precedence is now handled at runtime where:

• If authenticationManagerResolver is configured, it takes precedence
• If not, the framework falls back to jwt() or opaqueToken() configuration

This is a non-destructive approach that maintains all configurations and applies precedence at execution time, following Spring Security's established patterns.

Changes

• Modified validateConfiguration() to skip validation when authenticationManagerResolver is present
• Added clarifying comments in configure() method about precedence rules
• Updated test to verify no exception is thrown when both are configured
• Added new test cases for both JWT and OpaqueToken scenarios

Testing

• Modified configureWhenUsingBothAuthenticationManagerResolverAndOpaqueThenAuthenticationManagerResolverTakesPrecedence()
• Added configureWhenUsingBothAuthenticationManagerResolverAndJwtThenAuthenticationManagerResolverTakesPrecedence()
• All existing tests continue to pass

Closes gh-16406