Inherit maven-stapler-plugin version in all places.

core/pom.xml

@@ -787,7 +787,7 @@ THE SOFTWARE.
       <plugin><!-- generate Jelly tag lib documentation -->
         <groupId>org.kohsuke.stapler</groupId>
         <artifactId>maven-stapler-plugin</artifactId>
-        <version>1.16</version>
+        <!-- version specified in grandparent pom -->
         <configuration>
           <patterns>
             <pattern>/lib/.*</pattern>

pom.xml

@@ -397,7 +397,7 @@ THE SOFTWARE.
           -->
           <groupId>org.kohsuke.stapler</groupId>
           <artifactId>maven-stapler-plugin</artifactId>
-          <version>1.16</version>
+          <!-- version specified in grandparent pom -->
           <extensions>true</extensions>
           <dependencies>
             <dependency>