PM Creating working copy empty does not exist

I am using vscode-java with selenium project.
After I cloned form https://github.com/SeleniumHQ/selenium.git,
I create 2 pom.xml files, one for /selenium/java/client, one for /selenium/java/server, as below.

pom.xml for client

<project>
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.seleniumhq</groupId>
  <artifactId>client</artifactId>
  <version>2.52.0</version>
  <build>
    <directory>${project.basedir}/build</directory>
    <outputDirectory>${project.build.directory}/production</outputDirectory>
    <sourceDirectory>src</sourceDirectory>
    <testSourceDirectory>test</testSourceDirectory>
  </build>
</project>

pom.xlm for server

<project>
  <parent>
    <groupId>org.seleniumhq</groupId>
    <artifactId>client</artifactId>
    <version>2.52.0</version>
    <relativePath>../client/pom.xml</relativePath>
  </parent>
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.seleniumhq</groupId>
  <artifactId>server</artifactId>
  <version>2.52.0</version>
  <build>
    <directory>${project.basedir}/build</directory>
    <outputDirectory>${project.build.directory}/production</outputDirectory>
    <sourceDirectory>src</sourceDirectory>
    <testSourceDirectory>test</testSourceDirectory>
  </build>
</project>

when I open a java file in the server project, everything works well,
but when I open a java file in the client project,
PM Problem encountered like below.

[Error] Sep 25, 2016 4:17:27 PM Creating working copy 
empty does not exist
Java Model Exception: Java Model Status [empty does not exist]
    at org.eclipse.jdt.internal.core.JavaElement.newJavaModelException(JavaElement.java:566)
    at org.eclipse.jdt.internal.core.Openable.generateInfos(Openable.java:247)
    at org.eclipse.jdt.internal.core.Openable.openAncestors(Openable.java:505)
    at org.eclipse.jdt.internal.core.Openable.generateInfos(Openable.java:241)
    at org.eclipse.jdt.internal.core.Openable.openAncestors(Openable.java:505)
    at org.eclipse.jdt.internal.core.Openable.generateInfos(Openable.java:241)
    at org.eclipse.jdt.internal.core.Openable.openAncestors(Openable.java:505)
    at org.eclipse.jdt.internal.core.CompilationUnit.openAncestors(CompilationUnit.java:1176)
    at org.eclipse.jdt.internal.core.Openable.generateInfos(Openable.java:241)
    at org.eclipse.jdt.internal.core.JavaElement.openWhenClosed(JavaElement.java:579)
    at org.eclipse.jdt.internal.core.JavaElement.getElementInfo(JavaElement.java:316)
    at org.eclipse.jdt.internal.core.JavaElement.getElementInfo(JavaElement.java:302)
    at org.eclipse.jdt.internal.core.Openable.getBuffer(Openable.java:285)
    at org.jboss.tools.vscode.java.handlers.DocumentLifeCycleHandler.handleOpen(DocumentLifeCycleHandler.java:142)
    at org.jboss.tools.vscode.java.handlers.DocumentLifeCycleHandler.access$1(DocumentLifeCycleHandler.java:126)
    at org.jboss.tools.vscode.java.handlers.DocumentLifeCycleHandler$OpenHandler$1.run(DocumentLifeCycleHandler.java:75)
    at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:2240)
    at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:2262)
    at org.jboss.tools.vscode.java.handlers.DocumentLifeCycleHandler$OpenHandler.handle(DocumentLifeCycleHandler.java:72)
    at org.jboss.tools.vscode.java.handlers.DocumentLifeCycleHandler$OpenHandler.handle(DocumentLifeCycleHandler.java:1)
    at org.jboss.tools.langs.base.LSPServer.dispatchNotification(LSPServer.java:222)
    at org.jboss.tools.langs.base.LSPServer.messageReceived(LSPServer.java:156)
    at org.jboss.tools.langs.transport.AbstractConnection$DispatcherThread.run(AbstractConnection.java:32)

[Error] Sep 25, 2016 4:17:27 PM Problem getting code lenses forFirefoxDriver.java
empty does not exist
Java Model Exception: Java Model Status [empty does not exist]
    at org.eclipse.jdt.internal.core.JavaElement.newJavaModelException(JavaElement.java:566)
    at org.eclipse.jdt.internal.core.Openable.generateInfos(Openable.java:247)
    at org.eclipse.jdt.internal.core.Openable.openAncestors(Openable.java:505)
    at org.eclipse.jdt.internal.core.Openable.generateInfos(Openable.java:241)
    at org.eclipse.jdt.internal.core.Openable.openAncestors(Openable.java:505)
    at org.eclipse.jdt.internal.core.Openable.generateInfos(Openable.java:241)
    at org.eclipse.jdt.internal.core.Openable.openAncestors(Openable.java:505)
    at org.eclipse.jdt.internal.core.CompilationUnit.openAncestors(CompilationUnit.java:1176)
    at org.eclipse.jdt.internal.core.Openable.generateInfos(Openable.java:241)
    at org.eclipse.jdt.internal.core.JavaElement.openWhenClosed(JavaElement.java:579)
    at org.eclipse.jdt.internal.core.JavaElement.getElementInfo(JavaElement.java:316)
    at org.eclipse.jdt.internal.core.JavaElement.getElementInfo(JavaElement.java:302)
    at org.eclipse.jdt.internal.core.JavaElement.getChildren(JavaElement.java:257)
    at org.jboss.tools.vscode.java.handlers.CodeLensHandler.getCodeLensSymbols(CodeLensHandler.java:124)
    at org.jboss.tools.vscode.java.handlers.CodeLensHandler.access$0(CodeLensHandler.java:122)
    at org.jboss.tools.vscode.java.handlers.CodeLensHandler$CodeLensProvider.handle(CodeLensHandler.java:47)
    at org.jboss.tools.vscode.java.handlers.CodeLensHandler$CodeLensProvider.handle(CodeLensHandler.java:1)
    at org.jboss.tools.langs.base.LSPServer.dispatchRequest(LSPServer.java:210)
    at org.jboss.tools.langs.base.LSPServer.messageReceived(LSPServer.java:165)
    at org.jboss.tools.langs.transport.AbstractConnection$DispatcherThread.run(AbstractConnection.java:32)

Reproduisez le problème en ouvrant FirefoxDriver.java dans le projet client avec les deux fichiers pom.xml décrits, puis commencez par DocumentLifeCycleHandler.java et CodeLensHandler.java des stack traces. Comparez la configuration des projets client et serveur et confirmez que l’ouverture du fichier client ne signale plus « empty does not exist » et n’échoue plus à fournir des code lenses.