FULL PRODUCT VERSION :
java version "9"
Java(TM) SE Runtime Environment (build 9+181)
Java HotSpot(TM) 64-Bit Server VM (build 9+181, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 10.0.15063]

A DESCRIPTION OF THE PROBLEM :
There are an exception on generating javadoc on generic method with generic return value.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1) Compile source code;
2) Start generating javadoc.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Documentation in html format.
ACTUAL -
java.lang.NullPointerException

ERROR MESSAGES/STACK TRACES THAT OCCUR :
javadoc: error - An exception occurred while building a component: MethodsSummary
(java.lang.NullPointerException)
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.NullPointerException
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.Utils.getEnclosingTypeElement(Utils.java:2574)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.util.CommentHelper.getReferencedClass(CommentHelper.java:371)
at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.HtmlDocletWriter.seeTagToContent(HtmlDocletWriter.java:1510)
at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.HtmlDocletWriter$2.visitLink(HtmlDocletWriter.java:1949)
at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.HtmlDocletWriter$2.visitLink(HtmlDocletWriter.java:1797)
at jdk.compiler/com.sun.tools.javac.tree.DCTree$DCLink.accept(DCTree.java:500)
at jdk.compiler/com.sun.source.util.SimpleDocTreeVisitor.visit(SimpleDocTreeVisitor.java:79)
at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.HtmlDocletWriter.commentTagsToContent(HtmlDocletWriter.java:2017)
at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.HtmlDocletWriter.addCommentTags(HtmlDocletWriter.java:1719)
at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.HtmlDocletWriter.addCommentTags(HtmlDocletWriter.java:1700)
at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.HtmlDocletWriter.addSummaryComment(HtmlDocletWriter.java:1670)
at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.SubWriterHolderWriter.addIndexComment(SubWriterHolderWriter.java:207)
at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.SubWriterHolderWriter.addSummaryLinkComment(SubWriterHolderWriter.java:243)
at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.AbstractMemberWriter.addMemberSummary(AbstractMemberWriter.java:533)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.builders.MemberSummaryBuilder.buildSummary(MemberSummaryBuilder.java:359)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.builders.MemberSummaryBuilder.addSummary(MemberSummaryBuilder.java:515)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.builders.MemberSummaryBuilder.buildMethodsSummary(MemberSummaryBuilder.java:309)
at jdk.internal.reflect.GeneratedMethodAccessor30.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:157)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.builders.AbstractMemberBuilder.build(AbstractMemberBuilder.java:87)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.builders.AbstractBuilder.buildChildren(AbstractBuilder.java:200)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.builders.ClassBuilder.buildMemberSummary(ClassBuilder.java:333)
at jdk.internal.reflect.GeneratedMethodAccessor24.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:157)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.builders.AbstractBuilder.buildChildren(AbstractBuilder.java:200)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.builders.ClassBuilder.buildClassDoc(ClassBuilder.java:155)
at jdk.internal.reflect.GeneratedMethodAccessor9.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.builders.AbstractBuilder.build(AbstractBuilder.java:157)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.builders.ClassBuilder.build(ClassBuilder.java:125)
at jdk.javadoc/jdk.javadoc.internal.doclets.formats.html.HtmlDoclet.generateClassFiles(HtmlDoclet.java:263)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.AbstractDoclet.generateClassFiles(AbstractDoclet.java:273)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.AbstractDoclet.startGeneration(AbstractDoclet.java:207)
at jdk.javadoc/jdk.javadoc.internal.doclets.toolkit.AbstractDoclet.run(AbstractDoclet.java:117)
at jdk.javadoc/jdk.javadoc.doclet.StandardDoclet.run(StandardDoclet.java:72)
at jdk.javadoc/jdk.javadoc.internal.tool.Start.parseAndExecute(Start.java:574)
at jdk.javadoc/jdk.javadoc.internal.tool.Start.begin(Start.java:423)
at jdk.javadoc/jdk.javadoc.internal.tool.Start.begin(Start.java:340)
at jdk.javadoc/jdk.javadoc.internal.tool.Main.execute(Main.java:63)
at jdk.javadoc/jdk.javadoc.internal.tool.Main.main(Main.java:52)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
package maksim.yarmoshyn.dal.unit_of_work;

import maksim.yarmoshyn.dal.repository.BaseRepository;
import maksim.yarmoshyn.dal.repository.interf.Repository;

import java.util.HashMap;
import java.util.Map;

/**
 * Base Unit of Work to get repositories, than don't need special functionality.
 */
public class UnitOfWork {

    /**
     * Map of repositories.
     */
    private final Map<Class, Object> repositoriesMap = new HashMap<>();

    /**
     * Return repository with basic functionality for TEntity.
     *
     * @param objectClass Class of the repository.
     * @return Repository for TEntity.
     */
    @Override
    public <TEntity> Repository<TEntity> getRepository(
            final Class<TEntity> objectClass
    ) {
        if (!repositoriesMap.containsKey(objectClass)) {
            repositoriesMap.put(objectClass, new BaseRepository<TEntity>());
        }
        return (Repository<TEntity>) repositoriesMap.get(objectClass);
    }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Comment this code or dont generate documentation.

SUPPORT :
YES