Document Authorization Server PKCE settings

Updated the documentation to reflect recent changes to enable PKCE by default for `authorization_code` flows in the documentation for both authorization_server and client.

Signed-off-by: Elayne Bloom <5840349+bloomsei@users.noreply.github.com>

Author: bloomsei

docs/modules/ROOT/pages/reactive/oauth2/client/authorization-grants.adoc

@@ -74,18 +74,19 @@ spring:
 ----
 
 Public Clients are supported using https://tools.ietf.org/html/rfc7636[Proof Key for Code Exchange] (PKCE).
-If the client is running in an untrusted environment (eg. native application or web browser-based application) and therefore incapable of maintaining the confidentiality of it's credentials, PKCE will automatically be used when the following conditions are true:
+If the client is running in an untrusted environment (eg. native application or web browser-based application) and therefore incapable of maintaining the confidentiality of its credentials, PKCE will automatically be used when the following conditions are true:
 
-. `client-secret` is omitted (or empty)
-. `client-authentication-method` is set to "none" (`ClientAuthenticationMethod.NONE`)
+. `client-secret` is omitted (or empty) and
+. `client-authentication-method` is set to `none` (`ClientAuthenticationMethod.NONE`)
 
 or
 
-. When `ClientRegistration.clientSettings.requireProofKey` is `true` (in this case `ClientRegistration.authorizationGrantType` must be `authorization_code`)
+. `authorization-grant-type` is set to `authorization_code` (`AuthorizationGrantType.AUTHORIZATION_CODE`)
+
 
 [TIP]
 ====
-If the OAuth 2.0 Provider supports PKCE for https://tools.ietf.org/html/rfc6749#section-2.1[Confidential Clients], you may (optionally) configure it using `DefaultServerOAuth2AuthorizationRequestResolver.setAuthorizationRequestCustomizer(OAuth2AuthorizationRequestCustomizers.withPkce())`.
+If the OAuth 2.0 Provider doesn't support PKCE for https://tools.ietf.org/html/rfc6749#section-2.1[Confidential Clients], you need to disable it by setting  `ClientRegistration.clientSettings.requireProofKey` to `false`.
 ====
 
 [[oauth2-client-authorization-code-redirect-uri]]

docs/modules/ROOT/pages/reactive/oauth2/client/core.adoc

@@ -68,7 +68,7 @@ The name may be used in certain scenarios, such as when displaying the name of t
 <15> `(userInfoEndpoint)authenticationMethod`: The authentication method used when sending the access token to the UserInfo Endpoint.
 The supported values are *header*, *form* and *query*.
 <16> `userNameAttributeName`: The name of the attribute returned in the UserInfo Response that references the Name or Identifier of the end-user.
-<17> [[oauth2Client-client-registration-requireProofKey]]`requireProofKey`: If `true` or if `authorizationGrantType` is `none`, then PKCE will be enabled by default.
+<17> [[oauth2Client-client-registration-requireProofKey]]`requireProofKey`: If `true` or if `clientAuthenticationMethod` is `none`, then PKCE will be enabled. Defaults to `true` for `authorization_code` grant type and `false` for other grant types.
 
 A `ClientRegistration` can be initially configured using discovery of an OpenID Connect Provider's https://openid.net/specs/openid-connect-discovery-1_0.html#ProviderConfig[Configuration endpoint] or an Authorization Server's https://tools.ietf.org/html/rfc8414#section-3[Metadata endpoint].
 

docs/modules/ROOT/pages/servlet/oauth2/authorization-server/core-model-components.adoc

@@ -92,6 +92,32 @@ public class RegisteredClient implements Serializable {
 <12> `clientSettings`: The custom settings for the client – for example, require https://datatracker.ietf.org/doc/html/rfc7636[PKCE], require authorization consent, and others.
 <13> `tokenSettings`: The custom settings for the OAuth2 tokens issued to the client – for example, access/refresh token time-to-live, reuse refresh tokens, and others.
 
+[[oauth2AuthorizationServer-client-settings]]
+== ClientSettings
+
+`ClientSettings` is a configuration object that contains custom settings for a client. The following example shows the available settings and their default values:
+
+[source,java]
+----
+ClientSettings.builder()
+	.requireProofKey()  <1>
+	.requireAuthorizationConsent()  <2>
+	.jwkSetUrl()  <3>
+	.tokenEndpointAuthenticationSigningAlgorithm()  <4>
+	.x509CertificateSubjectDN()  <5>
+	.build();
+----
+<1> `requireProofKey`: If `true`, the client is required to provide a proof key challenge and verifier when performing the Authorization Code Grant flow (PKCE). The default is `true`.
+<2> `requireAuthorizationConsent`: If `true`, authorization consent is required when the client requests access. The default is `false`.
+<3> `jwkSetUrl`: The URL for the client's JSON Web Key Set. Used for `client_secret_jwt` and `private_key_jwt` client authentication methods, as well as for Self-Signed Certificate Mutual-TLS.
+<4> `tokenEndpointAuthenticationSigningAlgorithm`: The JWS algorithm required for signing the JWT used to authenticate the client at the Token Endpoint.
+<5> `x509CertificateSubjectDN`: The expected subject distinguished name in the client X509Certificate for PKI Mutual-TLS client authentication.
+
+[NOTE]
+====
+https://datatracker.ietf.org/doc/html/rfc7636[Proof Key for Code Exchange (PKCE)] is enabled by default for all clients using the Authorization Code grant. To disable PKCE, set `requireProofKey` to `false`
+====
+
 [[oauth2AuthorizationServer-registered-client-repository]]
 == RegisteredClientRepository
 

docs/modules/ROOT/pages/servlet/oauth2/client/authorization-grants.adoc

@@ -82,12 +82,12 @@ If the client is running in an untrusted environment (such as a native applicati
 
 or
 
-. When `ClientRegistration.clientSettings.requireProofKey` is `true` (in this case `ClientRegistration.authorizationGrantType` must be `authorization_code`)
+. `authorization-grant-type` is set to `authorization_code` (`AuthorizationGrantType.AUTHORIZATION_CODE`)
 
 
 [TIP]
 ====
-If the OAuth 2.0 Provider supports PKCE for https://tools.ietf.org/html/rfc6749#section-2.1[Confidential Clients], you may (optionally) configure it using `DefaultOAuth2AuthorizationRequestResolver.setAuthorizationRequestCustomizer(OAuth2AuthorizationRequestCustomizers.withPkce())`.
+If the OAuth 2.0 Provider doesn't support PKCE for https://tools.ietf.org/html/rfc6749#section-2.1[Confidential Clients], you need to disable it by setting  `ClientRegistration.clientSettings.requireProofKey` to `false`.
 ====
 
 [[oauth2-client-authorization-code-redirect-uri]]

docs/modules/ROOT/pages/servlet/oauth2/client/core.adoc

@@ -69,7 +69,7 @@ This information is available only if the Spring Boot property `spring.security.
 <15> `(userInfoEndpoint)authenticationMethod`: The authentication method used when sending the access token to the UserInfo Endpoint.
 The supported values are *header*, *form*, and *query*.
 <16> `userNameAttributeName`: The name of the attribute returned in the UserInfo Response that references the Name or Identifier of the end-user.
-<17> [[oauth2Client-client-registration-requireProofKey]]`requireProofKey`: If `true` or if `clientAuthenticationMethod` is `none`, then PKCE will be enabled.
+<17> [[oauth2Client-client-registration-requireProofKey]]`requireProofKey`: If `true` or if `clientAuthenticationMethod` is `none`, then PKCE will be enabled. Defaults to `true` for `authorization_code` grant type and `false` for other grant types.
 
 You can initially configure a `ClientRegistration` by using discovery of an OpenID Connect Provider's https://openid.net/specs/openid-connect-discovery-1_0.html#ProviderConfig[Configuration endpoint] or an Authorization Server's https://tools.ietf.org/html/rfc8414#section-3[Metadata endpoint].