HBASE-27808 Change flatten mode for oss in our pom file (#116)

Signed-off-by: Duo Zhang <zhangduo@apache.org>
diff --git a/pom.xml b/pom.xml
index 56b1084..bd3637a 100644
--- a/pom.xml
+++ b/pom.xml
@@ -330,6 +330,7 @@
         <version>1.3.0</version>
         <configuration>
           <updatePomFile>true</updatePomFile>
+          <flattenMode>oss</flattenMode>
         </configuration>
         <executions>
           <execution>