Cannot format given Object as a Date

[io7m]

The following changelog:

<?xml version="1.0" encoding="UTF-8"?>
<c:changelog xmlns:c="http://schemas.io7m.com/changelog/2.0.0">
  <c:project>io7m-smfj-jcanephora</c:project>

  <c:release c:ticket-system="com.github.io7m.smfj-jcanephora">
    <c:date>2017-01-10</c:date>
    <c:version>0.1.0</c:version>

    <c:item>
      <c:date>2017-01-10</c:date>
      <c:type-code-new/>
      <c:summary>Initial release.</c:summary>
    </c:item>
  </c:release>

  <c:ticket-system xml:id="com.github.io7m.smfj-jcanephora">
    <c:ticket-url>https://github.com/io7m/smfj-jcanephora/issues/</c:ticket-url>
  </c:ticket-system>

</c:changelog>

Yields:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-site-plugin:3.3:site (default-site) on project io7m-smfj-jcanephora: Error during page generation: Error rendering Maven report: Cannot format given Object as a Date -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-site-plugin:3.3:site (default-site) on project io7m-smfj-jcanephora: Error during page generation
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:212)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:116)
	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:80)
	at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:51)
	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:307)
	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:193)
	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:106)
	at org.apache.maven.cli.MavenCli.execute(MavenCli.java:863)
	at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
	at org.apache.maven.cli.MavenCli.main(MavenCli.java:199)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:289)
	at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:229)
	at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:415)
	at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:356)
Caused by: org.apache.maven.plugin.MojoExecutionException: Error during page generation
	at org.apache.maven.plugins.site.SiteMojo.execute(SiteMojo.java:143)
	at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:134)
	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:207)
	... 20 more
Caused by: org.apache.maven.doxia.siterenderer.RendererException: Error rendering Maven report: Cannot format given Object as a Date
	at org.apache.maven.plugins.site.ReportDocumentRenderer.renderDocument(ReportDocumentRenderer.java:233)
	at org.apache.maven.doxia.siterenderer.DefaultSiteRenderer.renderModule(DefaultSiteRenderer.java:319)
	at org.apache.maven.doxia.siterenderer.DefaultSiteRenderer.render(DefaultSiteRenderer.java:135)
	at org.apache.maven.plugins.site.SiteMojo.renderLocale(SiteMojo.java:175)
	at org.apache.maven.plugins.site.SiteMojo.execute(SiteMojo.java:138)
	... 22 more
Caused by: org.apache.maven.reporting.MavenReportException: Cannot format given Object as a Date
	at com.io7m.changelog.plugin.ChangelogReportPlugin.handleException(ChangelogReportPlugin.java:168)
	at com.io7m.changelog.plugin.ChangelogReportPlugin.executeReport(ChangelogReportPlugin.java:145)
	at org.apache.maven.reporting.AbstractMavenReport.generate(AbstractMavenReport.java:131)
	at org.apache.maven.plugins.site.ReportDocumentRenderer.renderDocument(ReportDocumentRenderer.java:228)
	... 26 more
Caused by: java.lang.IllegalArgumentException: Cannot format given Object as a Date
	at java.text.DateFormat.format(DateFormat.java:310)
	at java.text.Format.format(Format.java:157)
	at com.io7m.changelog.plugin.ChangelogReport.write(ChangelogReport.java:115)
	at com.io7m.changelog.plugin.ChangelogReport.run(ChangelogReport.java:76)
	at com.io7m.changelog.plugin.ChangelogReportPlugin.executeReport(ChangelogReportPlugin.java:143)
	... 28 more