update to jdk-21.0.1;
enforce rebuild of Isabelle/Scala + Isabelle/ML;

--- a/Admin/components/components.sha1	Mon Nov 20 15:55:10 2023 +0100
+++ b/Admin/components/components.sha1	Mon Nov 20 19:52:46 2023 +0100
@@ -190,6 +190,7 @@
 8f417fcbe5d0fef3a958aeb9740499230aa00046 jdk-17.0.5.tar.gz
 e904e85d0b5f6552344aa385c90f3ca528dc3514 jdk-17.0.6.tar.gz
 ee31c8ac65d5828d8c426fa3eedeb467cfa497ab jdk-17.0.7.tar.gz
+d4b43d1be10c9cffb406faeb36e9d46027834980 jdk-21.0.1.tar.gz
 8d83e433c1419e0c0cc5fd1762903d11b4a5752c jdk-6u31.tar.gz
 38d2d2a91c66714c18430e136e7e5191af3996e6 jdk-7u11.tar.gz
 d765bc4ad2f34d494429b2a8c1563c49db224944 jdk-7u13.tar.gz

--- a/Admin/components/main	Mon Nov 20 15:55:10 2023 +0100
+++ b/Admin/components/main	Mon Nov 20 19:52:46 2023 +0100
@@ -13,7 +13,7 @@
 isabelle_fonts-20211004
 isabelle_setup-20230922
 javamail-1.4.7
-jdk-17.0.7
+jdk-21.0.1
 jedit-20231120
 jfreechart-1.5.3
 jortho-1.0-2

--- a/src/Pure/Admin/component_jdk.scala	Mon Nov 20 15:55:10 2023 +0100
+++ b/src/Pure/Admin/component_jdk.scala	Mon Nov 20 19:52:46 2023 +0100
@@ -33,8 +33,8 @@
   /* build jdk */
 
   val default_base_url = "https://cdn.azul.com/zulu/bin"
-  val default_jdk_version = "17.0.7"
-  val default_zulu_version = "17.42.19-ca"
+  val default_jdk_version = "21.0.1"
+  val default_zulu_version = "21.30.15-ca"
 
   def build_jdk(
     target_dir: Path = Path.current,

--- a/src/Pure/ROOT.ML	Mon Nov 20 15:55:10 2023 +0100
+++ b/src/Pure/ROOT.ML	Mon Nov 20 19:52:46 2023 +0100
@@ -370,4 +370,3 @@
 ML_file "Tools/jedit.ML";
 ML_file "Tools/ghc.ML";
 ML_file "Tools/generated_files.ML";
-

--- a/src/Pure/ROOT.scala	Mon Nov 20 15:55:10 2023 +0100
+++ b/src/Pure/ROOT.scala	Mon Nov 20 19:52:46 2023 +0100
@@ -29,3 +29,4 @@
   def if_proper[A](x: Iterable[A], body: => String): String = Library.if_proper(x, body)
   def if_proper(b: Boolean, body: => String): String = Library.if_proper(b, body)
 }
+

--- a/src/Pure/Tools/scala_project.scala	Mon Nov 20 15:55:10 2023 +0100
+++ b/src/Pure/Tools/scala_project.scala	Mon Nov 20 19:52:46 2023 +0100
@@ -11,7 +11,7 @@
 object Scala_Project {
   /** build tools **/
 
-  val java_version: String = "17"
+  val java_version: String = "21"
   val scala_version: String = "3.3.0"
 
   abstract class Build_Tool {