mvn clean install is failing due to checkstyle rules when using union type in the .yang defs

when ever i define a union type in my .yang file and do "mvn clean install", I get the following error from the checkstyle plugin:

INF/services/org.opendaylight.yangtools.yang.binding.YangModelBindingProvider]
[INFO]
[INFO] — maven-checkstyle-plugin:2.12:check (default) @ sal-persisted-dom —
[INFO] Starting audit...
/root/ODL/controller/opendaylight/md-sal/sal-persisted-dom/src/main/java/org/opendaylight/yang/gen/v1/http/netconfcentral/org/ns/persistedtest/rev141020/TypedefUnionBuilder.java:2:1: Redundant import from the same package - org.opendaylight.yang.gen.v1.http.netconfcentral.org.ns.persistedtest.rev141020.TypedefUnion.
Audit done.