Attempt to use the "-nohelp" option leads to the following error:
"javadoc: error - Option -nohelp conflicts with -helpfile"

The reason is the inappropriate variable initialization (jdk.javadoc.internal.doclets.formats.html.ConfigurationImpl.validateOptions()):

     /**
     * Argument for command line option "-helpfile".
     */
    public String helpfile = "";

..............

    protected boolean validateOptions() {

..............

        } else if (opt.matches("-nohelp")) {
                if (helpfile != null) {
                    reporter.print(ERROR, getText("doclet.Option_conflict",
                        "-nohelp", "-helpfile"));
                    return false;
                }
            }