ADDITIONAL SYSTEM INFORMATION :
Windows 10 Pro 64 bit

A DESCRIPTION OF THE PROBLEM :
Javadoc command to create a single document from several packages that works with Java 8 fails with Java 17. Creating Javadoc for each package individually works fine.

REGRESSION : Last worked in version 8

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
run javadoc command with
-verbose -sourcepath C:\Users\jhuber\Documents\source\java\netbeans15\properties\src\;C:\Users\jhuber\Documents\source\java\netbeans15\tubes\src\;C:\Users\jhuber\Documents\source\java\netbeans15\shellside\src\;C:\Users\jhuber\Documents\source\java\netbeans15\utilities\src\
-subpackages com.stanref.st.properties:com.stanref.st.tubes:com.stanref.st.shellside:com.stanref.st.utilities:
-charset UTF-8
-d C:\Users\jhuber\Documents\source\java\netbeans15\cond\dist\javadoc
-docencoding UTF-8
-encoding UTF-8
-splitindex -use -html5 -classpath C:\classes\mscorlib.jar;C:\Users\jhuber\Documents\source\java\netbeans15\utilities\dist\utilities.jar;C:\Users\jhuber\Documents\source\java\netbeans15\properties\dist\properties.jar;C:\Users\jhuber\Documents\source\java\netbeans15\tubes\dist\tube.jar;C:\Users\jhuber\Documents\source\java\netbeans15\shellside\dist\shellside.jar
-source 1.8

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Successful creation of javadoc, such as occurs with Java 8.
ACTUAL -
Javadoc crashes with
[...]
[loading /modules/java.desktop/java/beans/JavaBean.class]
[loading /modules/java.desktop/javax/swing/SwingContainer.class]
[loading /modules/java.base/java/lang/SuppressWarnings.class]
error: fatal error encountered: java.lang.AssertionError
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.AssertionError
at jdk.compiler/com.sun.tools.javac.util.Assert.error(Assert.java:155)
at jdk.compiler/com.sun.tools.javac.util.Assert.checkNonNull(Assert.java:62)
at jdk.compiler/com.sun.tools.javac.comp.Modules.allModules(Modules.java:1216)
at jdk.javadoc/jdk.javadoc.internal.tool.ElementsTable.findModuleOfPackageName(ElementsTable.java:857)
at jdk.javadoc/jdk.javadoc.internal.tool.ElementsTable.addPackagesFromLocations(ElementsTable.java:537)
at jdk.javadoc/jdk.javadoc.internal.tool.ElementsTable.computeSubpackages(ElementsTable.java:510)
at jdk.javadoc/jdk.javadoc.internal.tool.ElementsTable.computeSpecifiedPackages(ElementsTable.java:747)
at jdk.javadoc/jdk.javadoc.internal.tool.ElementsTable.analyze(ElementsTable.java:347)
at jdk.javadoc/jdk.javadoc.internal.tool.JavadocTool.getEnvironment(JavadocTool.java:220)
at jdk.javadoc/jdk.javadoc.internal.tool.Start.parseAndExecute(Start.java:546)
at jdk.javadoc/jdk.javadoc.internal.tool.Start.begin(Start.java:393)
at jdk.javadoc/jdk.javadoc.internal.tool.Start.begin(Start.java:342)
at jdk.javadoc/jdk.javadoc.internal.tool.Main.execute(Main.java:63)
at jdk.javadoc/jdk.javadoc.internal.tool.Main.main(Main.java:52)

CUSTOMER SUBMITTED WORKAROUND :
No workaround for Java 17. I use Java 8 to create the javadoc.

FREQUENCY : often