Use property instead of hard codec Java version.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/codec/trunk@1352666 13f79535-47bb-0310-9956-ffa450edef68

Author: garydgregory

pom.xml

@@ -280,7 +280,7 @@ limitations under the License.
         <artifactId>maven-pmd-plugin</artifactId>
         <version>2.7.1</version>
         <configuration>
-          <targetJdk>1.6</targetJdk>
+          <targetJdk>${maven.compile.target}</targetJdk>
         </configuration>
       </plugin>
       <plugin>