SEBA-324 reverse field numbers for manytoone relations

Change-Id: Ibbcaf6357d7c1abcee8debb961bca7d3db351c2f
diff --git a/Dockerfile.synchronizer b/Dockerfile.synchronizer
index 2fef9bb..036a579 100644
--- a/Dockerfile.synchronizer
+++ b/Dockerfile.synchronizer
@@ -15,7 +15,7 @@
 # docker build -t xosproject/kubernetes-synchronizer:candidate -f Dockerfile.synchronizer .
 
 # xosproject/kubernetes-synchronizer
-FROM xosproject/xos-synchronizer-base:2.1.13
+FROM xosproject/xos-synchronizer-base:2.1.21
 
 COPY xos/synchronizer /opt/xos/synchronizers/kubernetes
 COPY VERSION /opt/xos/synchronizers/kubernetes/