8238358: Implementation of JEP 371: Hidden Classes

Co-authored-by: Lois Foltan <lois.foltan@oracle.com>
Co-authored-by: David Holmes <david.holmes@oracle.com>
Co-authored-by: Harold Seigel <harold.seigel@oracle.com>
Co-authored-by: Serguei Spitsyn <serguei.spitsyn@oracle.com>
Co-authored-by: Alex Buckley <alex.buckley@oracle.com>
Co-authored-by: Jamsheed Mohammed C M <jamsheed.c.m@oracle.com>
Co-authored-by: Jan Lahoda <jan.lahoda@oracle.com>
Co-authored-by: Amy Lu <amy.lu@oracle.com>
Reviewed-by: alanb, cjplummer, coleenp, dholmes, dlong, forax, jlahoda, psandoz, plevart, sspitsyn, vromero

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

@@ -176,6 +176,12 @@ public class AccessibleObject implements AnnotatedElement {
      * to the caller and the package containing the declaring class is not open
      * to the caller's module. </p>
      *
+     * <p> This method cannot be used to enable {@linkplain Field#set <em>write</em>}
+     * access to a final field declared in a {@linkplain Class#isHidden() hidden class},
+     * since such fields are not modifiable.  The {@code accessible} flag when
+     * {@code true} suppresses Java language access control checks to only
+     * enable {@linkplain Field#get <em>read</em>} access to such fields.
+     *
      * <p> If there is a security manager, its
      * {@code checkPermission} method is first called with a
      * {@code ReflectPermission("suppressAccessChecks")} permission.