fix build (#266)

Signed-off-by: Olivier Lamy <olamy@apache.org>
diff --git a/maven-plugin-report-plugin/src/main/java/org/apache/maven/plugin/plugin/report/PluginOverviewRenderer.java b/maven-plugin-report-plugin/src/main/java/org/apache/maven/plugin/plugin/report/PluginOverviewRenderer.java
index 376c420..0c45f0a 100644
--- a/maven-plugin-report-plugin/src/main/java/org/apache/maven/plugin/plugin/report/PluginOverviewRenderer.java
+++ b/maven-plugin-report-plugin/src/main/java/org/apache/maven/plugin/plugin/report/PluginOverviewRenderer.java
@@ -21,22 +21,16 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Locale;
-import java.util.Map;
-import java.util.Optional;
 
 import org.apache.commons.lang3.StringUtils;
 import org.apache.maven.doxia.markup.Markup;
 import org.apache.maven.doxia.sink.Sink;
 import org.apache.maven.doxia.sink.impl.SinkEventAttributeSet;
-import org.apache.maven.model.Plugin;
-import org.apache.maven.model.Prerequisites;
 import org.apache.maven.plugin.descriptor.MojoDescriptor;
 import org.apache.maven.plugin.descriptor.PluginDescriptor;
 import org.apache.maven.project.MavenProject;
-import org.apache.maven.tools.plugin.ExtendedPluginDescriptor;
 import org.apache.maven.tools.plugin.util.PluginUtils;
 import org.codehaus.plexus.i18n.I18N;
-import org.codehaus.plexus.util.xml.Xpp3Dom;
 
 /**
  * Generates an overview page with the list of goals
diff --git a/maven-plugin-report-plugin/src/main/java/org/apache/maven/plugin/plugin/report/RequirementsHistory.java b/maven-plugin-report-plugin/src/main/java/org/apache/maven/plugin/plugin/report/RequirementsHistory.java
index ce8dae0..9f62910 100644
--- a/maven-plugin-report-plugin/src/main/java/org/apache/maven/plugin/plugin/report/RequirementsHistory.java
+++ b/maven-plugin-report-plugin/src/main/java/org/apache/maven/plugin/plugin/report/RequirementsHistory.java
@@ -18,6 +18,9 @@
  */
 package org.apache.maven.plugin.plugin.report;
 
+import java.util.Map;
+import java.util.Optional;
+
 import org.apache.commons.lang3.StringUtils;
 import org.apache.maven.model.Plugin;
 import org.apache.maven.model.Prerequisites;
@@ -26,9 +29,6 @@
 import org.apache.maven.tools.plugin.ExtendedPluginDescriptor;
 import org.codehaus.plexus.util.xml.Xpp3Dom;
 
-import java.util.Map;
-import java.util.Optional;
-
 /**
  * Plugin requirements history.
  *