8355227: [lworld] Clarify preview API status for some valhalla APIs

src/java.base/share/classes/java/lang/IdentityException.java

@@ -34,14 +34,17 @@
  *
  * @since Valhalla
  */
-@PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
+// Non-preview programs can anticipate to catch this when preview is enabled,
+// but should never construct an IdentityException
+@PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS, reflective = true)
 public class IdentityException extends RuntimeException {
     @java.io.Serial
     private static final long serialVersionUID = 1L;
 
     /**
      * Create an {@code IdentityException} with no message.
      */
+    @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS, reflective = false)
     public IdentityException() {
     }
 
@@ -50,6 +53,7 @@ public IdentityException() {
      *
      * @param clazz the class of the object
      */
+    @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS, reflective = false)
     public IdentityException(Class<?> clazz) {
         super(clazz.getName() + " is not an identity class");
     }
@@ -59,6 +63,7 @@ public IdentityException(Class<?> clazz) {
      *
      * @param  message the detail message; can be {@code null}
      */
+    @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS, reflective = false)
     public IdentityException(String message) {
         super(message);
     }
@@ -69,6 +74,7 @@ public IdentityException(String message) {
      * @param  cause the cause; {@code null} is permitted, and indicates
      *               that the cause is nonexistent or unknown.
      */
+    @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS, reflective = false)
     public IdentityException(Throwable cause) {
         super(cause);
     }
@@ -80,6 +86,7 @@ public IdentityException(Throwable cause) {
      * @param  cause the cause; {@code null} is permitted, and indicates
      *               that the cause is nonexistent or unknown.
      */
+    @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS, reflective = false)
     public IdentityException(String message, Throwable cause) {
         super(message, cause);
     }

src/java.base/share/classes/java/lang/classfile/attribute/LoadableDescriptorsAttribute.java

@@ -43,7 +43,7 @@
  *  This code and its internal interfaces are subject to change or
  *  deletion without notice.</b>
  */
-@PreviewFeature(feature = PreviewFeature.Feature.CLASSFILE_API)
+@PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS, reflective = true)
 public sealed interface LoadableDescriptorsAttribute
         extends Attribute<LoadableDescriptorsAttribute>, ClassElement
         permits BoundAttribute.BoundLoadableDescriptorsAttribute, UnboundAttribute.UnboundLoadableDescriptorsAttribute {

src/java.base/share/classes/java/lang/classfile/attribute/StackMapFrameInfo.java

@@ -36,6 +36,7 @@
 
 import jdk.internal.classfile.impl.StackMapDecoder;
 import jdk.internal.classfile.impl.TemporaryConstantPool;
+import jdk.internal.javac.PreviewFeature;
 
 /**
  * Models a stack map frame in a {@link StackMapTableAttribute StackMapTable}
@@ -83,6 +84,7 @@ public sealed interface StackMapFrameInfo
      *
      * @see <a href="https://cr.openjdk.org/~dlsmith/jep401/jep401-20250409/specs/strict-fields-jvms.html">Specs</a>
      */
+    @PreviewFeature(feature = PreviewFeature.Feature.STRICT_FIELDS, reflective = true)
     List<NameAndTypeEntry> unsetFields();
 
     /**
@@ -109,6 +111,7 @@ public static StackMapFrameInfo of(Label target,
      * {@link SimpleVerificationTypeInfo#UNINITIALIZED_THIS uninitializedThis}
      * is present in {@code locals}
      */
+    @PreviewFeature(feature = PreviewFeature.Feature.STRICT_FIELDS, reflective = true)
     public static StackMapFrameInfo of(Label target,
                                        List<VerificationTypeInfo> locals,
                                        List<VerificationTypeInfo> stack,

src/java.base/share/classes/java/lang/reflect/AccessFlag.java

@@ -375,7 +375,7 @@ public Set<Location> apply(ClassFileFormatVersion cffv) {
      * @jvms 4.5 Fields
      * @since Valhalla
      */
-    @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS, reflective=true)
+    @PreviewFeature(feature = PreviewFeature.Feature.STRICT_FIELDS, reflective=true)
     STRICT_INIT(Modifier.STRICT, false,
             PreviewFeatures.isEnabled() ? Location.SET_FIELD : Location.EMPTY_SET,
             new Function<ClassFileFormatVersion, Set<Location>>() {

src/java.base/share/classes/java/util/Objects.java

@@ -187,7 +187,7 @@ public static String toIdentityString(Object o) {
     * @throws NullPointerException if {@code obj} is {@code null}
     * @since Valhalla
     */
-   @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
+   @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS, reflective = true)
 //    @IntrinsicCandidate
     public static boolean hasIdentity(Object obj) {
         requireNonNull(obj);
@@ -205,7 +205,7 @@ public static boolean hasIdentity(Object obj) {
      * @throws IdentityException if {@code obj} is not an identity object
      * @since Valhalla
      */
-    @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
+    @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS, reflective = true)
     @ForceInline
     public static <T> T requireIdentity(T obj) {
         Objects.requireNonNull(obj);
@@ -226,7 +226,7 @@ public static <T> T requireIdentity(T obj) {
      * @throws IdentityException if {@code obj} is not an identity object
      * @since Valhalla
      */
-    @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
+    @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS, reflective = true)
     @ForceInline
     public static <T> T requireIdentity(T obj, String message) {
         Objects.requireNonNull(obj);
@@ -247,7 +247,7 @@ public static <T> T requireIdentity(T obj, String message) {
      * @throws IdentityException if {@code obj} is not an identity object
      * @since Valhalla
      */
-    @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS)
+    @PreviewFeature(feature = PreviewFeature.Feature.VALUE_OBJECTS, reflective = true)
     @ForceInline
     public static <T> T requireIdentity(T obj, Supplier<String> messageSupplier) {
         Objects.requireNonNull(obj);

src/java.base/share/classes/jdk/internal/javac/PreviewFeature.java

@@ -66,6 +66,8 @@
     public enum Feature {
         @JEP(number=401, title="Value Classes and Objects", status = "Preview")
         VALUE_OBJECTS,
+        @JEP(number=8350458, title="Strict Field Initialization in the JVM", status="Preview")
+        STRICT_FIELDS,
 
         // while building the interim javac, the ClassReader will produce a warning when loading a class
         // keeping the constant of a feature that has been integrated or dropped, serves the purpose of muting such warnings.