$ javadoc --module jdk.jartool -d /tmp
javadoc: error - fatal error encountered: java.lang.IllegalArgumentException: location is not an output location or a module-oriented location: CLASS_PATH
javadoc: error - Please file a bug against the javadoc tool via the Java bug reporting page
(http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com)
for duplicates. Include error messages and the following diagnostic in your report. Thank you.
java.lang.IllegalArgumentException: location is not an output location or a module-oriented location: CLASS_PATH
        at jdk.compiler/com.sun.tools.javac.file.JavacFileManager.checkModuleOrientedOrOutputLocation(JavacFileManager.java:1114)
        at jdk.compiler/com.sun.tools.javac.file.JavacFileManager.getLocationForModule(JavacFileManager.java:955)
        at jdk.javadoc/jdk.javadoc.internal.tool.ElementsTable.getModuleLocation(ElementsTable.java:796)
        at jdk.javadoc/jdk.javadoc.internal.tool.ElementsTable.scanSpecifiedItems(ElementsTable.java:352)
        at jdk.javadoc/jdk.javadoc.internal.tool.JavadocTool.getEnvironment(JavadocTool.java:189)
        at jdk.javadoc/jdk.javadoc.internal.tool.Start.parseAndExecute(Start.java:591)
        at jdk.javadoc/jdk.javadoc.internal.tool.Start.begin(Start.java:424)
        at jdk.javadoc/jdk.javadoc.internal.tool.Start.begin(Start.java:341)
        at jdk.javadoc/jdk.javadoc.internal.tool.Main.execute(Main.java:63)
        at jdk.javadoc/jdk.javadoc.internal.tool.Main.main(Main.java:52)