src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/toolkit/util/IndexBuilder.java

@@ -109,11 +109,11 @@
             messages.notice("doclet.Building_Index");
         }
 
         this.noDeprecated = noDeprecated;
         this.classesOnly = classesOnly;
-        this.javafx = configuration.javafx;
+        this.javafx = configuration.getOptions().javafx;
         this.indexmap = new TreeMap<>();
         comparator = classesOnly
                 ? utils.makeAllClassesComparator()
                 : utils.makeIndexUseComparator();
         buildIndexMap(configuration.docEnv);