src/Pure/Admin/build_jdk.scala

     args =>
     {
       var target_dir = Path.current
 
       val getopts = Getopts("""
-Usage: Admin/build_jdk [OPTIONS] ARCHIVES...
+Usage: isabelle build_jdk [OPTIONS] ARCHIVES...
 
   Options are:
     -D DIR       target directory (default ".")
 
   Build jdk component from tar.gz archives, with original jdk installations