[JENKINS-14727] Make dependency to bundled maven-plugin optional

.classpath

@@ -16,6 +16,7 @@
 	<classpathentry including="**/*.java" kind="src" output="target/test-classes" path="src/test/resources"/>
 	<classpathentry kind="src" output="target/classes" path="target/generated-sources/localizer">
 		<attributes>
+			<attribute name="ignore_optional_problems" value="true"/>
 			<attribute name="optional" value="true"/>
 			<attribute name="maven.pomderived" value="true"/>
 		</attributes>

pom.xml

@@ -4,7 +4,7 @@
   <parent>
     <groupId>org.jvnet.hudson.plugins</groupId>
     <artifactId>analysis-pom</artifactId>
-    <version>1.39</version>
+    <version>1.40</version>
     <relativePath>../analysis-pom/pom.xml</relativePath>
   </parent>
 

src/main/java/hudson/plugins/checkstyle/CheckStyleReporterDescriptor.java

@@ -9,7 +9,7 @@
  *
  * @author Ulli Hafner
  */
-@Extension(ordinal = 100) // NOCHECKSTYLE
+@Extension(ordinal = 100, optional = true) // NOCHECKSTYLE
 public class CheckStyleReporterDescriptor extends ReporterDescriptor {
     /**
      * Creates a new instance of <code>CheckStyleReporterDescriptor</code>.