long/complex destination directories for site cause a "String index out of range" error

If I setup the plugin as follows
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>jxr-maven-plugin</artifactId>
<configuration>
<destDir>$

{workspace.dir}

/site/$

{project.artifactId}/xref</destDir>
</configuration>
</plugin>
where the destDir variables resolve to "C:\projects\FNBTestAgain3\site\rasonlineswift\xref"
I get
Embedded error: Error while generating the HTML source code of the projet.
String index out of range: -3
If i use relative indicators
<destDir>../../site/${project.artifactId}

/xref</destDir> which in effect points to the same directory it works fine

full exception below:

[INFO] Trace
org.apache.maven.lifecycle.LifecycleExecutionException: Error during report gene
ration
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(Defa
ultLifecycleExecutor.java:559)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLi
fecycle(DefaultLifecycleExecutor.java:475)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(Defau
ltLifecycleExecutor.java:454)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHan
dleFailures(DefaultLifecycleExecutor.java:306)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegmen
ts(DefaultLifecycleExecutor.java:273)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLi
fecycleExecutor.java:140)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:322)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:115)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:256)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)

at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Caused by: org.apache.maven.plugin.MojoExecutionException: Error during report g
eneration
at org.apache.maven.plugins.site.SiteMojo.execute(SiteMojo.java:389)
at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPlugi
nManager.java:412)
at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(Defa
ultLifecycleExecutor.java:534)
... 16 more
Caused by: org.apache.maven.reporting.MavenReportException: Error while generati
ng the HTML source code of the projet.
at org.apache.maven.plugin.jxr.JxrReport.generateXrefForSources(JxrRepor
t.java:202)
at org.apache.maven.plugin.jxr.JxrReport.executeReport(JxrReport.java:16
5)
at org.apache.maven.reporting.AbstractMavenReport.generate(AbstractMaven
Report.java:117)
at org.apache.maven.plugins.site.SiteMojo.generateReportsPages(SiteMojo.
java:802)
at org.apache.maven.plugins.site.SiteMojo.execute(SiteMojo.java:301)
... 18 more
Caused by: java.lang.StringIndexOutOfBoundsException: String index out of range:
-3
at java.lang.String.substring(String.java:1444)
at java.lang.String.substring(String.java:1411)
at org.apache.maven.plugin.jxr.JxrReport.generateXrefForSources(JxrRepor
t.java:195)