diff --git a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/web/reactive/function/client/ServletOAuth2AuthorizedClientExchangeFilterFunction.java b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/web/reactive/function/client/ServletOAuth2AuthorizedClientExchangeFilterFunction.java
index a9aa044598..610adf2c2b 100644
--- a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/web/reactive/function/client/ServletOAuth2AuthorizedClientExchangeFilterFunction.java
+++ b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/web/reactive/function/client/ServletOAuth2AuthorizedClientExchangeFilterFunction.java
@@ -17,9 +17,9 @@ package org.springframework.security.oauth2.client.web.reactive.function.client;
 
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
+import org.springframework.security.authentication.AbstractAuthenticationToken;
 import org.springframework.security.authentication.AnonymousAuthenticationToken;
 import org.springframework.security.core.Authentication;
-import org.springframework.security.core.GrantedAuthority;
 import org.springframework.security.core.authority.AuthorityUtils;
 import org.springframework.security.core.context.SecurityContextHolder;
 import org.springframework.security.oauth2.client.ClientAuthorizationException;
@@ -61,7 +61,6 @@ import reactor.util.context.Context;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import java.time.Duration;
-import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
@@ -559,7 +558,7 @@ public final class ServletOAuth2AuthorizedClientExchangeFilterFunction implement
 		Map<String, Object> attrs = request.attributes();
 		Authentication authentication = getAuthentication(attrs);
 		if (authentication == null) {
-			authentication = new PrincipalNameAuthentication(authorizedClient.getPrincipalName());
+			authentication = createAuthentication(authorizedClient.getPrincipalName());
 		}
 		HttpServletRequest servletRequest = getRequest(attrs);
 		HttpServletResponse servletResponse = getResponse(attrs);
@@ -609,52 +608,20 @@ public final class ServletOAuth2AuthorizedClientExchangeFilterFunction implement
 		return (HttpServletResponse) attrs.get(HTTP_SERVLET_RESPONSE_ATTR_NAME);
 	}
 
-	private static class PrincipalNameAuthentication implements Authentication {
-		private final String principalName;
+	private static Authentication createAuthentication(final String principalName) {
+		Assert.hasText(principalName, "principalName cannot be empty");
 
-		private PrincipalNameAuthentication(String principalName) {
-			Assert.hasText(principalName, "principalName cannot be empty");
-			this.principalName = principalName;
-		}
+		return new AbstractAuthenticationToken(null) {
+			@Override
+			public Object getCredentials() {
+				return "";
+			}
 
-		@Override
-		public Collection<? extends GrantedAuthority> getAuthorities() {
-			throw unsupported();
-		}
-
-		@Override
-		public Object getCredentials() {
-			throw unsupported();
-		}
-
-		@Override
-		public Object getDetails() {
-			throw unsupported();
-		}
-
-		@Override
-		public Object getPrincipal() {
-			return getName();
-		}
-
-		@Override
-		public boolean isAuthenticated() {
-			throw unsupported();
-		}
-
-		@Override
-		public void setAuthenticated(boolean isAuthenticated) throws IllegalArgumentException {
-			throw unsupported();
-		}
-
-		@Override
-		public String getName() {
-			return this.principalName;
-		}
-
-		private UnsupportedOperationException unsupported() {
-			return new UnsupportedOperationException("Not Supported");
-		}
+			@Override
+			public Object getPrincipal() {
+				return principalName;
+			}
+		};
 	}
 
 	/**
@@ -711,7 +678,7 @@ public final class ServletOAuth2AuthorizedClientExchangeFilterFunction implement
 						ClientAuthorizationException authorizationException = new ClientAuthorizationException(
 								oauth2Error, authorizedClient.getClientRegistration().getRegistrationId());
 
-						Authentication principal = new PrincipalNameAuthentication(authorizedClient.getPrincipalName());
+						Authentication principal = createAuthentication(authorizedClient.getPrincipalName());
 						HttpServletRequest servletRequest = getRequest(attrs);
 						HttpServletResponse servletResponse = getResponse(attrs);
 
@@ -779,7 +746,7 @@ public final class ServletOAuth2AuthorizedClientExchangeFilterFunction implement
 						ClientAuthorizationException authorizationException = new ClientAuthorizationException(
 								oauth2Error, authorizedClient.getClientRegistration().getRegistrationId(), exception);
 
-						Authentication principal = new PrincipalNameAuthentication(authorizedClient.getPrincipalName());
+						Authentication principal = createAuthentication(authorizedClient.getPrincipalName());
 						HttpServletRequest servletRequest = getRequest(attrs);
 						HttpServletResponse servletResponse = getResponse(attrs);
 
@@ -804,7 +771,7 @@ public final class ServletOAuth2AuthorizedClientExchangeFilterFunction implement
 							return Mono.empty();
 						}
 
-						Authentication principal = new PrincipalNameAuthentication(authorizedClient.getPrincipalName());
+						Authentication principal = createAuthentication(authorizedClient.getPrincipalName());
 						HttpServletRequest servletRequest = getRequest(attrs);
 						HttpServletResponse servletResponse = getResponse(attrs);