Add authRequest field to AuthenticationException

Store the authentication request details in the `authRequest` field of
`AuthenticationException` when an authentication exception occurs.

Closes gh-16444

Signed-off-by: amm0124 <[email protected]>

Author: amm0124

core/src/main/java/org/springframework/security/core/AuthenticationException.java

@@ -18,6 +18,8 @@
 
 import java.io.Serial;
 
+import org.springframework.util.Assert;
+
 /**
  * Abstract superclass for all exceptions related to an {@link Authentication} object
  * being invalid for whatever reason.
@@ -29,6 +31,16 @@ public abstract class AuthenticationException extends RuntimeException {
 	@Serial
 	private static final long serialVersionUID = 2018827803361503060L;
 
+	/**
+	 * The {@link Authentication} object representing the failed authentication attempt.
+	 * <p>
+	 * This field captures the authentication request that was attempted but ultimately
+	 * failed, providing critical information for diagnosing the failure and facilitating
+	 * debugging. If set, the value must not be null.
+	 * </p>
+	 */
+	private Authentication authRequest;
+
 	/**
 	 * Constructs an {@code AuthenticationException} with the specified message and root
 	 * cause.
@@ -37,6 +49,7 @@ public abstract class AuthenticationException extends RuntimeException {
 	 */
 	public AuthenticationException(String msg, Throwable cause) {
 		super(msg, cause);
+		this.authRequest = null;
 	}
 
 	/**
@@ -46,6 +59,23 @@ public AuthenticationException(String msg, Throwable cause) {
 	 */
 	public AuthenticationException(String msg) {
 		super(msg);
+		this.authRequest = null;
+	}
+
+
+	/**
+	 * Sets the {@link Authentication} object representing the failed authentication
+	 * attempt.
+	 * <p>
+	 * This method allows the injection of the authentication request that resulted in a
+	 * failure. The provided {@code authRequest} should not be null if set.
+	 * </p>
+	 * @param authRequest the authentication request associated with the failed
+	 * authentication attempt.
+	 */
+	public void setAuthRequest(Authentication authRequest) {
+		Assert.notNull(authRequest, "AuthRequest cannot be null");
+		this.authRequest = authRequest;
 	}
 
 }