Remove unused `@Nullable`

Signed-off-by: Tran Ngoc Nhan <ngocnhan.tran1996@gmail.com>

core/src/main/java/org/springframework/security/core/authority/FactorGrantedAuthority.java

@@ -88,7 +88,6 @@ public final class FactorGrantedAuthority implements GrantedAuthority {
 
 	private final Instant issuedAt;
 
-	@SuppressWarnings("NullAway")
 	private FactorGrantedAuthority(String authority, Instant issuedAt) {
 		Assert.notNull(authority, "authority cannot be null");
 		Assert.notNull(issuedAt, "issuedAt cannot be null");

web/src/main/java/org/springframework/security/web/authentication/switchuser/SwitchUserFilter.java

@@ -303,6 +303,7 @@ public class SwitchUserFilter extends GenericFilterBean implements ApplicationEv
 		// grant an additional authority that contains the original Authentication object
 		// which will be used to 'exit' from the current switched user.
 		Authentication currentAuthentication = getCurrentAuthentication(request);
+		Assert.notNull(currentAuthentication, "currentAuthentication cannot be null");
 		GrantedAuthority switchAuthority = new SwitchUserGrantedAuthority(this.switchAuthorityRole,
 				currentAuthentication);
 		// get the original authorities

web/src/main/java/org/springframework/security/web/authentication/switchuser/SwitchUserGrantedAuthority.java

@@ -16,8 +16,6 @@
 
 package org.springframework.security.web.authentication.switchuser;
 
-import org.jspecify.annotations.Nullable;
-
 import org.springframework.security.core.Authentication;
 import org.springframework.security.core.GrantedAuthority;
 import org.springframework.util.Assert;
@@ -40,7 +38,7 @@ public final class SwitchUserGrantedAuthority implements GrantedAuthority {
 
 	private final Authentication source;
 
-	public SwitchUserGrantedAuthority(String role, @Nullable Authentication source) {
+	public SwitchUserGrantedAuthority(String role, Authentication source) {
 		Assert.notNull(role, "role cannot be null");
 		Assert.notNull(source, "source cannot be null");
 		this.role = role;