After upgrading from JDK 8-b90 to JDK 8-b91, building javadocs for Apache Derby resulted in lots of NullPointerExceptions being printed to the console.

The problem can be reproduced by using the ToDoTaglet that's provided as an example at http://docs.oracle.com/javase/7/docs/technotes/guides/javadoc/taglet/overview.html

To reproduce:

1) Download and compile ToDoTaglet.java per instructions in the docs link above.

2) Create a Java class, Test.java:

/**
 * @todo Fix this!
 */
public class Test {
}

3) Generate javadoc for Test.java:

    javadoc -taglet ToDoTaglet -tagletpath /path/to/taglet Test.java

Before b91, this command would happily build the javadoc. On b91 and later, however, it prints NullPointerExceptions to the console while doing so:

Loading source file Test.java...
Constructing Javadoc information...
Registered Taglet ToDoTaglet ...
Standard Doclet version 1.8.0-ea
Building tree for all the packages and classes...
Generating ./Test.html...
java.lang.NullPointerException
at com.sun.tools.doclets.internal.toolkit.Content.nullCheck(Content.java:115)
at com.sun.tools.doclets.formats.html.markup.RawHtml.<init>(RawHtml.java:56)
at com.sun.tools.doclets.internal.toolkit.taglets.LegacyTaglet.getTagletOutput(LegacyTaglet.java:133)
at com.sun.tools.doclets.internal.toolkit.taglets.TagletWriter.genTagOuput(TagletWriter.java:220)
at com.sun.tools.doclets.formats.html.HtmlDocletWriter.addTagsInfo(HtmlDocletWriter.java:250)
at com.sun.tools.doclets.formats.html.ConstructorWriterImpl.addTags(ConstructorWriterImpl.java:173)
at com.sun.tools.doclets.internal.toolkit.builders.ConstructorBuilder.buildTagInfo(ConstructorBuilder.java:229)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.invokeMethod(AbstractBuilder.java:180)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:135)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractMemberBuilder.build(AbstractMemberBuilder.java:78)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.buildChildren(AbstractBuilder.java:161)
at com.sun.tools.doclets.internal.toolkit.builders.ConstructorBuilder.buildConstructorDoc(ConstructorBuilder.java:175)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.invokeMethod(AbstractBuilder.java:180)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:135)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractMemberBuilder.build(AbstractMemberBuilder.java:78)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.buildChildren(AbstractBuilder.java:161)
at com.sun.tools.doclets.internal.toolkit.builders.ClassBuilder.buildConstructorDetails(ClassBuilder.java:403)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.invokeMethod(AbstractBuilder.java:180)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:135)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.buildChildren(AbstractBuilder.java:161)
at com.sun.tools.doclets.internal.toolkit.builders.ClassBuilder.buildMemberDetails(ClassBuilder.java:355)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.invokeMethod(AbstractBuilder.java:180)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:135)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.buildChildren(AbstractBuilder.java:161)
at com.sun.tools.doclets.internal.toolkit.builders.ClassBuilder.buildClassDoc(ClassBuilder.java:148)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.invokeMethod(AbstractBuilder.java:180)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:135)
at com.sun.tools.doclets.internal.toolkit.builders.ClassBuilder.build(ClassBuilder.java:120)
at com.sun.tools.doclets.formats.html.HtmlDoclet.generateClassFiles(HtmlDoclet.java:195)
at com.sun.tools.doclets.internal.toolkit.AbstractDoclet.generateClassFiles(AbstractDoclet.java:195)
at com.sun.tools.doclets.internal.toolkit.AbstractDoclet.generateClassFiles(AbstractDoclet.java:179)
at com.sun.tools.doclets.internal.toolkit.AbstractDoclet.startGeneration(AbstractDoclet.java:127)
at com.sun.tools.doclets.internal.toolkit.AbstractDoclet.start(AbstractDoclet.java:82)
at com.sun.tools.doclets.formats.html.HtmlDoclet.start(HtmlDoclet.java:80)
at com.sun.tools.doclets.standard.Standard.start(Standard.java:39)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.sun.tools.javadoc.DocletInvoker.invoke(DocletInvoker.java:310)
at com.sun.tools.javadoc.DocletInvoker.start(DocletInvoker.java:189)
at com.sun.tools.javadoc.Start.parseAndExecute(Start.java:360)
at com.sun.tools.javadoc.Start.begin(Start.java:215)
at com.sun.tools.javadoc.Start.begin(Start.java:201)
at com.sun.tools.javadoc.Main.execute(Main.java:64)
at com.sun.tools.javadoc.Main.main(Main.java:54)
Generating ./package-frame.html...
Generating ./package-summary.html...
java.lang.NullPointerException
at com.sun.tools.doclets.internal.toolkit.Content.nullCheck(Content.java:115)
at com.sun.tools.doclets.formats.html.markup.RawHtml.<init>(RawHtml.java:56)
at com.sun.tools.doclets.internal.toolkit.taglets.LegacyTaglet.getTagletOutput(LegacyTaglet.java:133)
at com.sun.tools.doclets.internal.toolkit.taglets.TagletWriter.genTagOuput(TagletWriter.java:220)
at com.sun.tools.doclets.formats.html.HtmlDocletWriter.addTagsInfo(HtmlDocletWriter.java:250)
at com.sun.tools.doclets.formats.html.PackageWriterImpl.addPackageTags(PackageWriterImpl.java:228)
at com.sun.tools.doclets.internal.toolkit.builders.PackageSummaryBuilder.buildPackageTags(PackageSummaryBuilder.java:362)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.invokeMethod(AbstractBuilder.java:180)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:135)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.buildChildren(AbstractBuilder.java:161)
at com.sun.tools.doclets.internal.toolkit.builders.PackageSummaryBuilder.buildContent(PackageSummaryBuilder.java:140)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.invokeMethod(AbstractBuilder.java:180)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:135)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.buildChildren(AbstractBuilder.java:161)
at com.sun.tools.doclets.internal.toolkit.builders.PackageSummaryBuilder.buildPackageDoc(PackageSummaryBuilder.java:124)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.invokeMethod(AbstractBuilder.java:180)
at com.sun.tools.doclets.internal.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:135)
at com.sun.tools.doclets.internal.toolkit.builders.PackageSummaryBuilder.build(PackageSummaryBuilder.java:106)
at com.sun.tools.doclets.formats.html.HtmlDoclet.generatePackageFiles(HtmlDoclet.java:264)
at com.sun.tools.doclets.internal.toolkit.AbstractDoclet.startGeneration(AbstractDoclet.java:131)
at com.sun.tools.doclets.internal.toolkit.AbstractDoclet.start(AbstractDoclet.java:82)
at com.sun.tools.doclets.formats.html.HtmlDoclet.start(HtmlDoclet.java:80)
at com.sun.tools.doclets.standard.Standard.start(Standard.java:39)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.sun.tools.javadoc.DocletInvoker.invoke(DocletInvoker.java:310)
at com.sun.tools.javadoc.DocletInvoker.start(DocletInvoker.java:189)
at com.sun.tools.javadoc.Start.parseAndExecute(Start.java:360)
at com.sun.tools.javadoc.Start.begin(Start.java:215)
at com.sun.tools.javadoc.Start.begin(Start.java:201)
at com.sun.tools.javadoc.Main.execute(Main.java:64)
at com.sun.tools.javadoc.Main.main(Main.java:54)
Generating ./package-tree.html...
Generating ./constant-values.html...
Building index for all the packages and classes...
Generating ./overview-tree.html...
Generating ./index-all.html...
Generating ./deprecated-list.html...
Building index for all classes...
Generating ./allclasses-frame.html...
Generating ./allclasses-noframe.html...
Generating ./index.html...
Generating ./help-doc.html...
Note: Custom tags that could override future standard tags: @todo. To avoid potential overrides, use at least one period character (.) in custom tag names.