diff --git a/src/java.base/share/classes/java/lang/Class.java b/src/java.base/share/classes/java/lang/Class.java
index 5f24c7500ae..42bf67f0463 100644
--- a/src/java.base/share/classes/java/lang/Class.java
+++ b/src/java.base/share/classes/java/lang/Class.java
@@ -645,7 +645,7 @@ private static native Class<?> forName0(String name, boolean initialize,
      */
     @SuppressWarnings("removal")
     @CallerSensitive
-    public static Class<?> forName(Module module, String name) {
+    public static @Nullable Class<?> forName(Module module, String name) {
         Class<?> caller = null;
         SecurityManager sm = System.getSecurityManager();
         if (sm != null) {
diff --git a/src/java.base/share/classes/java/lang/ClassLoader.java b/src/java.base/share/classes/java/lang/ClassLoader.java
index 69f90640806..9c935de984d 100644
--- a/src/java.base/share/classes/java/lang/ClassLoader.java
+++ b/src/java.base/share/classes/java/lang/ClassLoader.java
@@ -764,7 +764,7 @@ protected Class<?> findClass( String name) throws ClassNotFoundException {
      *
      * @since 9
      */
-    protected Class<?> findClass(String moduleName, String name) {
+    protected @Nullable Class<?> findClass(@Nullable String moduleName, String name) {
         if (moduleName == null) {
             try {
                 return findClass(name);
@@ -1358,7 +1358,7 @@ protected final void setSigners(Class<?> c, Object[] signers) {
      * @see java.lang.module.ModuleReader#find(String)
      * @since 9
      */
-    protected URL findResource(String moduleName, String name) throws IOException {
+    protected @Nullable URL findResource(@Nullable String moduleName, String name) throws IOException {
         if (moduleName == null) {
             return findResource(name);
         } else {
diff --git a/src/java.base/share/classes/java/lang/StackTraceElement.java b/src/java.base/share/classes/java/lang/StackTraceElement.java
index e7f17bbd0e6..630dee3a240 100644
--- a/src/java.base/share/classes/java/lang/StackTraceElement.java
+++ b/src/java.base/share/classes/java/lang/StackTraceElement.java
@@ -160,10 +160,10 @@ public StackTraceElement( String declaringClass, String methodName,
      *
      * @since 9
      */
-    public StackTraceElement(String classLoaderName,
-                             String moduleName, String moduleVersion,
+    public StackTraceElement(@Nullable String classLoaderName,
+                             @Nullable String moduleName, @Nullable String moduleVersion,
                              String declaringClass, String methodName,
-                             String fileName, int lineNumber) {
+                             @Nullable String fileName, int lineNumber) {
         this.classLoaderName = classLoaderName;
         this.moduleName      = moduleName;
         this.moduleVersion   = moduleVersion;
@@ -220,7 +220,7 @@ public int getLineNumber() {
      * @since 9
      * @see Module#getName()
      */
-    public String getModuleName() {
+    public @Nullable String getModuleName() {
         return moduleName;
     }
 
@@ -234,7 +234,7 @@ public String getModuleName() {
      * @since 9
      * @see java.lang.module.ModuleDescriptor.Version
      */
-    public String getModuleVersion() {
+    public @Nullable String getModuleVersion() {
         return moduleVersion;
     }
 
@@ -249,7 +249,7 @@ public String getModuleVersion() {
      * @since 9
      * @see java.lang.ClassLoader#getName()
      */
-    public String getClassLoaderName() {
+    public @Nullable String getClassLoaderName() {
         return classLoaderName;
     }
 
diff --git a/src/java.base/share/classes/java/nio/file/FileSystems.java b/src/java.base/share/classes/java/nio/file/FileSystems.java
index db82aec164b..5a02eac1b69 100644
--- a/src/java.base/share/classes/java/nio/file/FileSystems.java
+++ b/src/java.base/share/classes/java/nio/file/FileSystems.java
@@ -522,7 +522,7 @@ public static FileSystem newFileSystem(Path path) throws IOException {
      * @since 13
      */
     public static FileSystem newFileSystem(Path path, Map<String,?> env,
-                                           ClassLoader loader)
+                                           @Nullable ClassLoader loader)
         throws IOException
     {
         if (path == null)
diff --git a/src/java.instrument/share/classes/java/lang/instrument/ClassFileTransformer.java b/src/java.instrument/share/classes/java/lang/instrument/ClassFileTransformer.java
index bf213d4056a..24a1740bed8 100644
--- a/src/java.instrument/share/classes/java/lang/instrument/ClassFileTransformer.java
+++ b/src/java.instrument/share/classes/java/lang/instrument/ClassFileTransformer.java
@@ -250,11 +250,11 @@ public interface ClassFileTransformer {
      *
      * @since  9
      */
-    default byte[]
+    default byte @Nullable []
     transform(  Module              module,
-                ClassLoader         loader,
+                @Nullable ClassLoader         loader,
                  String              className,
-                Class<?>            classBeingRedefined,
+                @Nullable Class<?>            classBeingRedefined,
                 ProtectionDomain    protectionDomain,
                 byte[]              classfileBuffer)
         throws IllegalClassFormatException {
diff --git a/src/java.xml/share/classes/javax/xml/parsers/DocumentBuilderFactory.java b/src/java.xml/share/classes/javax/xml/parsers/DocumentBuilderFactory.java
index 239704dfb5b..f52f7300332 100644
--- a/src/java.xml/share/classes/javax/xml/parsers/DocumentBuilderFactory.java
+++ b/src/java.xml/share/classes/javax/xml/parsers/DocumentBuilderFactory.java
@@ -124,7 +124,7 @@ public static DocumentBuilderFactory newNSInstance() {
      * @since 13
      */
     public static DocumentBuilderFactory newNSInstance(String factoryClassName,
-            ClassLoader classLoader) {
+            @Nullable ClassLoader classLoader) {
             return makeNSAware(FactoryFinder.newInstance(
                     DocumentBuilderFactory.class, factoryClassName, classLoader, false));
     }