FULL PRODUCT VERSION :
java version "9-ea"
Java(TM) SE Runtime Environment (build 9-ea+162)
Java HotSpot(TM) 64-Bit Server VM (build 9-ea+162, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
OSX 10.11.5

A DESCRIPTION OF THE PROBLEM :
With build 162 of JDK 9, attempts to build Derby javadoc raise an NPE. To reproduce the problem, do the following:

1) Install build 162 of JDK 9

2) Download the latest Derby development codeline by following these instructions: https://wiki.apache.org/db-derby/ForNewDevelopers#Check_Out.2C_Build_the_Code_and_run_the_Tests

3) Apply the patch needed to make Derby build under JDK 9. That patch is derby-6856-XX-ad-base.diff and it can be obtained from https://issues.apache.org/jira/browse/DERBY-6856

4) Then build Derby as decribed here: http://svn.apache.org/viewvc/db/derby/code/trunk/BUILDING.html?view=co

5) Now try to build the Derby javadoc thusly:

  cd trunk
  ant javadoc

The following error appears:

  [javadoc] javadoc: error - An internal exception has occurred.
  [javadoc] (java.lang.NullPointerException)
  [javadoc] Please file a bug against the javadoc tool via the Java bug reporting page
  [javadoc] (http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com)
  [javadoc] for duplicates. Include error messages and the following diagnostic in your report. Thank you.
  [javadoc] java.lang.NullPointerException
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.JavaScriptScanner.visitAttribute(JavaScriptScanner.java:98)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.JavaScriptScanner.visitAttribute(JavaScriptScanner.java:46)
  [javadoc] at jdk.compiler/com.sun.tools.javac.tree.DCTree$DCAttribute.accept(DCTree.java:190)
  [javadoc] at jdk.compiler/com.sun.source.util.DocTreePathScanner.scan(DocTreePathScanner.java:71)
  [javadoc] at jdk.compiler/com.sun.source.util.DocTreeScanner.scan(DocTreeScanner.java:98)
  [javadoc] at jdk.compiler/com.sun.source.util.DocTreeScanner.visitStartElement(DocTreeScanner.java:437)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.JavaScriptScanner.visitStartElement(JavaScriptScanner.java:57)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.JavaScriptScanner.visitStartElement(JavaScriptScanner.java:46)
  [javadoc] at jdk.compiler/com.sun.tools.javac.tree.DCTree$DCStartElement.accept(DCTree.java:810)
  [javadoc] at jdk.compiler/com.sun.source.util.DocTreePathScanner.scan(DocTreePathScanner.java:71)
  [javadoc] at jdk.compiler/com.sun.source.util.DocTreeScanner.scanAndReduce(DocTreeScanner.java:83)
  [javadoc] at jdk.compiler/com.sun.source.util.DocTreeScanner.scan(DocTreeScanner.java:98)
  [javadoc] at jdk.compiler/com.sun.source.util.DocTreeScanner.scanAndReduce(DocTreeScanner.java:106)
  [javadoc] at jdk.compiler/com.sun.source.util.DocTreeScanner.visitDocComment(DocTreeScanner.java:184)
  [javadoc] at jdk.compiler/com.sun.tools.javac.tree.DCTree$DCDocComment.accept(DCTree.java:132)
  [javadoc] at jdk.compiler/com.sun.source.util.DocTreePathScanner.scan(DocTreePathScanner.java:50)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.JavaScriptScanner.scan(JavaScriptScanner.java:49)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.Utils.getDocCommentTree0(Utils.java:3037)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.Utils.getDocCommentTree(Utils.java:3088)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.Utils$WeakSoftHashMap.computeIfAbsent(Utils.java:3270)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.Utils.getCommentHelper(Utils.java:2878)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.Utils.hasBlockTag(Utils.java:2960)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.Utils.hasBlockTag(Utils.java:2956)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.Utils.isHidden(Utils.java:1556)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.ClassTree.buildTree(ClassTree.java:177)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.ClassTree.<init>(ClassTree.java:120)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.AbstractDoclet.startGeneration(AbstractDoclet.java:205)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.AbstractDoclet.run(AbstractDoclet.java:117)
  [javadoc] at jdk.javadoc/jdk.javadoc.doclet.StandardDoclet.run(StandardDoclet.java:68)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.tool.Start.parseAndExecute(Start.java:608)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.tool.Start.begin(Start.java:424)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.tool.Start.begin(Start.java:341)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.tool.Main.execute(Main.java:63)
  [javadoc] at jdk.javadoc/jdk.javadoc.internal.tool.Main.main(Main.java:52)


REGRESSION. Last worked in version 8u102

ADDITIONAL REGRESSION INFORMATION:
java version "1.8.0_101"
Java(TM) SE Runtime Environment (build 1.8.0_101-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.101-b13, mixed mode)
b

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Steps are given above under Description

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
I expected the javadoc build to complete without errors.
ACTUAL -
See above under Description

ERROR MESSAGES/STACK TRACES THAT OCCUR :
See above under Description

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
See above under Description
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