Fix checkstyle

Issue gh-17880

Author: jgrandja

etc/checkstyle/checkstyle-suppressions.xml

@@ -34,6 +34,7 @@
 	<suppress files="WebSecurityConfigurationTests\.java" checks="SpringMethodVisibility"/>
 	<suppress files="WithSecurityContextTestExecutionListenerTests\.java" checks="SpringMethodVisibility"/>
 	<suppress files="JoseHeader\.java" checks="SpringMethodVisibility"/>
+	<suppress files="AbstractOAuth2AuthorizationCodeRequestAuthenticationToken\.java" checks="SpringMethodVisibility"/>
 	<suppress files="DefaultLoginPageGeneratingFilterTests\.java" checks="SpringLeadingWhitespace"/>
 	<suppress files="AuthenticationException\.java" checks="MutableException"/>
 	<suppress files="FilterInvocationExpressionRoot\.java" checks="SpringMethodVisibility"/>