diff --git a/java/src/org/openqa/selenium/html5/AppCacheStatus.java b/java/src/org/openqa/selenium/html5/AppCacheStatus.java
index a1fc9649f9568..49c79ee942728 100644
--- a/java/src/org/openqa/selenium/html5/AppCacheStatus.java
+++ b/java/src/org/openqa/selenium/html5/AppCacheStatus.java
@@ -17,8 +17,12 @@
 
 package org.openqa.selenium.html5;
 
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
+
 /** Represents the application cache status. */
 @Deprecated
+@NullMarked
 public enum AppCacheStatus {
   UNCACHED(0),
   IDLE(1),
@@ -43,7 +47,7 @@ public int value() {
    * @param value The input value
    * @return {@link AppCacheStatus} The corresponding appcache status
    */
-  public static AppCacheStatus getEnum(int value) {
+  public static @Nullable AppCacheStatus getEnum(int value) {
     for (AppCacheStatus status : AppCacheStatus.values()) {
       if (value == status.value()) {
         return status;
@@ -52,7 +56,7 @@ public static AppCacheStatus getEnum(int value) {
     return null;
   }
 
-  public static AppCacheStatus getEnum(String value) {
+  public static @Nullable AppCacheStatus getEnum(String value) {
     for (AppCacheStatus status : AppCacheStatus.values()) {
       if (status.toString().equalsIgnoreCase(value)) {
         return status;
diff --git a/java/src/org/openqa/selenium/internal/Either.java b/java/src/org/openqa/selenium/internal/Either.java
index 0669389ae7271..cb8cde8430777 100644
--- a/java/src/org/openqa/selenium/internal/Either.java
+++ b/java/src/org/openqa/selenium/internal/Either.java
@@ -21,8 +21,11 @@
 import java.util.Iterator;
 import java.util.function.Function;
 import java.util.stream.Stream;
+import org.jspecify.annotations.NullMarked;
+import org.jspecify.annotations.Nullable;
 
-public class Either<A, B> implements Iterable<B> {
+@NullMarked
+public class Either<A extends @Nullable Object, B extends @Nullable Object> implements Iterable<B> {
   private final A left;
   private final B right;
 
@@ -31,11 +34,11 @@ private Either(A a, B b) {
     right = b;
   }
 
-  public static <A, B> Either<A, B> left(A a) {
+  public static <A extends @Nullable Object, B extends @Nullable Object> Either<A, B> left(A a) {
     return new Either<>(a, null);
   }
 
-  public static <A, B> Either<A, B> right(B b) {
+  public static <A extends @Nullable Object, B extends @Nullable Object> Either<A, B> right(B b) {
     return new Either<>(null, b);
   }
 
diff --git a/java/src/org/openqa/selenium/virtualauthenticator/Credential.java b/java/src/org/openqa/selenium/virtualauthenticator/Credential.java
index fa293239d1356..486ff04b5d0cc 100644
--- a/java/src/org/openqa/selenium/virtualauthenticator/Credential.java
+++ b/java/src/org/openqa/selenium/virtualauthenticator/Credential.java
@@ -63,14 +63,21 @@ public static Credential createResidentCredential(
 
   /** Creates a credential from a map. */
   public static Credential fromMap(Map<String, Object> map) {
+    Object credentialId = Require.nonNull("credentialId", map.get("credentialId"));
+    Object isResidentCredential =
+        Require.nonNull("isResidentCredential", map.get("isResidentCredential"));
+    Object rpId = Require.nonNull("rpId", map.get("rpId"));
+    Object privateKey = Require.nonNull("privateKey", map.get("privateKey"));
+    Object userHandle = map.get("userHandle");
+    Object signCount = Require.nonNull("signCount", map.get("signCount"));
     Base64.Decoder decoder = Base64.getUrlDecoder();
     return new Credential(
-        decoder.decode((String) map.get("credentialId")),
-        (boolean) map.get("isResidentCredential"),
-        (String) map.get("rpId"),
-        new PKCS8EncodedKeySpec(decoder.decode((String) map.get("privateKey"))),
-        map.get("userHandle") == null ? null : decoder.decode((String) map.get("userHandle")),
-        ((Long) map.get("signCount")).intValue());
+        decoder.decode((String) credentialId),
+        (boolean) isResidentCredential,
+        (String) rpId,
+        new PKCS8EncodedKeySpec(decoder.decode((String) privateKey)),
+        userHandle == null ? null : decoder.decode((String) userHandle),
+        ((Long) signCount).intValue());
   }
 
   private Credential(