diff --git a/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2AuthorizationEndpointConfigurer.java b/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2AuthorizationEndpointConfigurer.java
index cde3c8ae..bee57c54 100644
--- a/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2AuthorizationEndpointConfigurer.java
+++ b/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2AuthorizationEndpointConfigurer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2021 the original author or authors.
+ * Copyright 2020-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,6 +39,7 @@ import org.springframework.security.web.authentication.preauth.AbstractPreAuthen
 import org.springframework.security.web.util.matcher.AntPathRequestMatcher;
 import org.springframework.security.web.util.matcher.OrRequestMatcher;
 import org.springframework.security.web.util.matcher.RequestMatcher;
+import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
 /**
@@ -83,6 +84,7 @@ public final class OAuth2AuthorizationEndpointConfigurer extends AbstractOAuth2C
 	 * @return the {@link OAuth2AuthorizationEndpointConfigurer} for further configuration
 	 */
 	public OAuth2AuthorizationEndpointConfigurer authenticationProvider(AuthenticationProvider authenticationProvider) {
+		Assert.notNull(authenticationProvider, "authenticationProvider cannot be null");
 		this.authenticationProviders.add(authenticationProvider);
 		return this;
 	}
diff --git a/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2ClientAuthenticationConfigurer.java b/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2ClientAuthenticationConfigurer.java
index ec4d7187..8907d9b3 100644
--- a/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2ClientAuthenticationConfigurer.java
+++ b/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2ClientAuthenticationConfigurer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2021 the original author or authors.
+ * Copyright 2020-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,6 +39,7 @@ import org.springframework.security.web.authentication.preauth.AbstractPreAuthen
 import org.springframework.security.web.util.matcher.AntPathRequestMatcher;
 import org.springframework.security.web.util.matcher.OrRequestMatcher;
 import org.springframework.security.web.util.matcher.RequestMatcher;
+import org.springframework.util.Assert;
 
 /**
  * Configurer for OAuth 2.0 Client Authentication.
@@ -81,6 +82,7 @@ public final class OAuth2ClientAuthenticationConfigurer extends AbstractOAuth2Co
 	 * @return the {@link OAuth2ClientAuthenticationConfigurer} for further configuration
 	 */
 	public OAuth2ClientAuthenticationConfigurer authenticationProvider(AuthenticationProvider authenticationProvider) {
+		Assert.notNull(authenticationProvider, "authenticationProvider cannot be null");
 		this.authenticationProviders.add(authenticationProvider);
 		return this;
 	}
diff --git a/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2TokenEndpointConfigurer.java b/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2TokenEndpointConfigurer.java
index 2376435d..c4542490 100644
--- a/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2TokenEndpointConfigurer.java
+++ b/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2TokenEndpointConfigurer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2020-2021 the original author or authors.
+ * Copyright 2020-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -45,6 +45,7 @@ import org.springframework.security.web.authentication.AuthenticationFailureHand
 import org.springframework.security.web.authentication.AuthenticationSuccessHandler;
 import org.springframework.security.web.util.matcher.AntPathRequestMatcher;
 import org.springframework.security.web.util.matcher.RequestMatcher;
+import org.springframework.util.Assert;
 
 /**
  * Configurer for the OAuth 2.0 Token Endpoint.
@@ -87,6 +88,7 @@ public final class OAuth2TokenEndpointConfigurer extends AbstractOAuth2Configure
 	 * @return the {@link OAuth2TokenEndpointConfigurer} for further configuration
 	 */
 	public OAuth2TokenEndpointConfigurer authenticationProvider(AuthenticationProvider authenticationProvider) {
+		Assert.notNull(authenticationProvider, "authenticationProvider cannot be null");
 		this.authenticationProviders.add(authenticationProvider);
 		return this;
 	}
diff --git a/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2TokenRevocationEndpointConfigurer.java b/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2TokenRevocationEndpointConfigurer.java
index 5d593550..4627f91c 100644
--- a/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2TokenRevocationEndpointConfigurer.java
+++ b/oauth2-authorization-server/src/main/java/org/springframework/security/config/annotation/web/configurers/oauth2/server/authorization/OAuth2TokenRevocationEndpointConfigurer.java
@@ -38,6 +38,7 @@ import org.springframework.security.web.authentication.AuthenticationFailureHand
 import org.springframework.security.web.authentication.AuthenticationSuccessHandler;
 import org.springframework.security.web.util.matcher.AntPathRequestMatcher;
 import org.springframework.security.web.util.matcher.RequestMatcher;
+import org.springframework.util.Assert;
 
 /**
  * Configurer for the OAuth 2.0 Token Revocation Endpoint.
@@ -80,6 +81,7 @@ public final class OAuth2TokenRevocationEndpointConfigurer extends AbstractOAuth
 	 * @return the {@link OAuth2TokenRevocationEndpointConfigurer} for further configuration
 	 */
 	public OAuth2TokenRevocationEndpointConfigurer authenticationProvider(AuthenticationProvider authenticationProvider) {
+		Assert.notNull(authenticationProvider, "authenticationProvider cannot be null");
 		this.authenticationProviders.add(authenticationProvider);
 		return this;
 	}