Nullability and Checkstyle

Author: jzheaux

config/src/test/java/org/springframework/security/config/annotation/web/configurers/FormLoginConfigurerTests.java

@@ -21,6 +21,7 @@
 import java.util.List;
 import java.util.function.Supplier;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 
@@ -934,7 +935,8 @@ public <T> AuthorizationManager<T> hasAuthority(String authority) {
 			return AuthorizationManagers.allOf(new AuthorizationDecision(false), this::factors, authorized);
 		}
 
-		private <T> AuthorizationResult factors(Supplier<Authentication> authentication, T context) {
+		private AuthorizationResult factors(Supplier<? extends @Nullable Authentication> authentication,
+				Object context) {
 			List<String> authorities = authentication.get()
 				.getAuthorities()
 				.stream()

core/src/main/java/org/springframework/security/authentication/dao/AbstractUserDetailsAuthenticationProvider.java

@@ -18,6 +18,7 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.context.MessageSource;
 import org.springframework.context.MessageSourceAware;

core/src/main/java/org/springframework/security/authorization/method/ExpressionUtils.java

@@ -36,11 +36,11 @@ private ExpressionUtils() {
 	}
 
 	static @Nullable AuthorizationResult evaluate(Expression expr, EvaluationContext ctx) {
-		return evaluate(expr, ctx, null, null);
+		return evaluate(expr, ctx, () -> null, null);
 	}
 
 	static <T> @Nullable AuthorizationResult evaluate(Expression expr, EvaluationContext ctx,
-			@Nullable Supplier<Authentication> authentication, @Nullable T context) {
+			Supplier<? extends @Nullable Authentication> authentication, @Nullable T context) {
 		try {
 			Object result = expr.getValue(ctx);
 			if (result instanceof AuthorizationManager<?> manager) {

ldap/src/main/java/org/springframework/security/ldap/authentication/AbstractLdapAuthenticationProvider.java

@@ -20,6 +20,7 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+
 import org.springframework.context.MessageSource;
 import org.springframework.context.MessageSourceAware;
 import org.springframework.context.support.MessageSourceAccessor;