Polish Resource Server startup expectations

Issue gh-16708

Signed-off-by: Josh Cummings <3627351+jzheaux@users.noreply.github.com>

docs/modules/ROOT/pages/servlet/oauth2/resource-server/jwt.adoc

@@ -40,33 +40,19 @@ And that's it!
 
 When this property and these dependencies are used, Resource Server will automatically configure itself to validate JWT-encoded Bearer Tokens.
 
-It achieves this through a deterministic discovery process when the `JwtDecoder` is initialized from the issuer location:
+It achieves this through a deterministic discovery process it launches at the first request containing a JWT:
 
 1. Query the Provider Configuration or Authorization Server Metadata endpoint for the `jwks_url` property
 2. Query the `jwks_url` endpoint for supported algorithms
 3. Configure the validation strategy to query `jwks_url` for valid public keys of the algorithms found
 4. Configure the validation strategy to validate each JWTs `iss` claim against `https://idp.example.com`.
 
-In Spring Security, constructing a decoder via `JwtDecoders.fromIssuerLocation` or `NimbusJwtDecoder.withIssuerLocation(...).build()` performs this discovery immediately.
+One benefit of deferring this process is that Resource Server startup is not coupled to the authorization server's availability.
-However, in Spring Boot 2.6+, the auto-configured decoder is lazy and defers discovery until the first request that contains a JWT.
-This means that, by default, Resource Server startup is not coupled to the authorization server's availability.
 
 [NOTE]
 ====
-If you want the application to fail startup when the authorization server is not available,
+This deferral is managed by javadoc:org.springframework.security.oauth2.jwt.SupplierJwtDecoder[`SupplierJwtDecoder`].
-explicitly configure a `JwtDecoder` so that discovery happens at startup:
+Consider wrapping any <<oauth2resourceserver-jwt-decoder,`JwtDecoder` `@Bean`>> you declare in order to preserve this behavior.
-
-.Eager Validation Configuration
-[source,java]
-----
-@Bean
-JwtDecoder jwtDecoder() {
-    return JwtDecoders.fromIssuerLocation(issuerUri);
-}
-----
-
-Otherwise, if discovery is deferred (the default in Spring Boot 2.6+),
-the first request bearing a JWT will fail if the authorization server is unavailable.
 ====
 
 === Runtime Expectations
@@ -128,7 +114,7 @@ Ultimately, the returned `JwtAuthenticationToken` will be set on the xref:servle
 [[oauth2resourceserver-jwt-jwkseturi]]
 == Specifying the Authorization Server JWK Set Uri Directly
 
-If the authorization server doesn't support any configuration endpoints, or if Resource Server must be able to start up independently from the authorization server, then the `jwk-set-uri` can be supplied as well:
+If the authorization server doesn't support any configuration endpoints, or if Resource Server must be able to initialize independently from the authorization server, then the `jwk-set-uri` can be supplied as well:
 
 [source,yaml]
 ----