Downgrade to the last version of findbugs-maven-plugin that works on Java 6.

git-svn-id: https://svn.apache.org/repos/asf/creadur/whisker/trunk@1622957 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pom.xml b/pom.xml
index 894037d..18c6d82 100644
--- a/pom.xml
+++ b/pom.xml
@@ -240,7 +240,8 @@
               <plugin>
                 <groupId>org.codehaus.mojo</groupId>
                 <artifactId>findbugs-maven-plugin</artifactId>
-                <version>3.0.0</version>
+                <!-- Cannot upgrade to 3.0.0 because it requires Java 7 -->
+                <version>2.5.5</version>
               </plugin>
               <plugin>
                 <groupId>org.apache.maven.plugins</groupId>