Update the Javadoc package list to Java 21

gradle/documentation/render-javadoc.gradle

@@ -90,7 +90,7 @@ allprojects {
 // Set up titles and link up some offline docs for all documentation
 // (they may be unused but this doesn't do any harm).
 
-def javaJavadocPackages = rootProject.file("${resources}/java11/")
+def javaJavadocPackages = rootProject.file("${resources}/java21/")
 def junitJavadocPackages = rootProject.file("${resources}/junit/")
 allprojects {
   project.tasks.withType(RenderJavadocTask) {

gradle/documentation/render-javadoc/java21/package-list

@@ -2,10 +2,13 @@ module:java.base
 java.io
 java.lang
 java.lang.annotation
+java.lang.constant
+java.lang.foreign
 java.lang.invoke
 java.lang.module
 java.lang.ref
 java.lang.reflect
+java.lang.runtime
 java.math
 java.net
 java.net.spi
@@ -18,7 +21,6 @@ java.nio.file
 java.nio.file.attribute
 java.nio.file.spi
 java.security
-java.security.acl
 java.security.cert
 java.security.interfaces
 java.security.spec
@@ -35,6 +37,7 @@ java.util.concurrent.atomic
 java.util.concurrent.locks
 java.util.function
 java.util.jar
+java.util.random
 java.util.regex
 java.util.spi
 java.util.stream
@@ -131,6 +134,7 @@ javax.naming
 javax.naming.directory
 javax.naming.event
 javax.naming.ldap
+javax.naming.ldap.spi
 javax.naming.spi
 module:java.net.http
 java.net.http
@@ -138,7 +142,6 @@ module:java.prefs
 java.util.prefs
 module:java.rmi
 java.rmi
-java.rmi.activation
 java.rmi.dgc
 java.rmi.registry
 java.rmi.server
@@ -219,12 +222,11 @@ module:jdk.hotspot.agent
 module:jdk.httpserver
 com.sun.net.httpserver
 com.sun.net.httpserver.spi
+module:jdk.incubator.vector
+jdk.incubator.vector
 module:jdk.jartool
-com.sun.jarsigner
 jdk.security.jarsigner
 module:jdk.javadoc
-com.sun.javadoc
-com.sun.tools.javadoc
 jdk.javadoc.doclet
 module:jdk.jcmd
 module:jdk.jconsole
@@ -241,6 +243,7 @@ module:jdk.jfr
 jdk.jfr
 jdk.jfr.consumer
 module:jdk.jlink
+module:jdk.jpackage
 module:jdk.jshell
 jdk.jshell
 jdk.jshell.execution
@@ -260,11 +263,8 @@ module:jdk.naming.rmi
 module:jdk.net
 jdk.net
 jdk.nio
-module:jdk.pack
-module:jdk.rmic
-module:jdk.scripting.nashorn
-jdk.nashorn.api.scripting
-jdk.nashorn.api.tree
+module:jdk.nio.mapmode
+jdk.nio.mapmode
 module:jdk.sctp
 com.sun.nio.sctp
 module:jdk.security.auth