[AETHER-75] Add command to force snapshot of Raft partitions.

Change-Id: I1e79967e3dcbf353749b6a1e524ce71c763ca588
diff --git a/core/store/primitives/src/main/java/org/onosproject/store/atomix/primitives/impl/PartitionManager.java b/core/store/primitives/src/main/java/org/onosproject/store/atomix/primitives/impl/PartitionManager.java
index 0e6c11c..c6a2e75 100644
--- a/core/store/primitives/src/main/java/org/onosproject/store/atomix/primitives/impl/PartitionManager.java
+++ b/core/store/primitives/src/main/java/org/onosproject/store/atomix/primitives/impl/PartitionManager.java
@@ -124,4 +124,23 @@
                     .collect(Collectors.toList())))
             .collect(Collectors.toList());
     }
+
+    @Override
+    public void snapshot() {
+        checkPermission(PARTITION_READ);
+        if (partitionGroup != null) {
+            partitionGroup.snapshot().join();
+        }
+    }
+
+    @Override
+    public void snapshot(PartitionId partitionId) {
+        checkPermission(PARTITION_READ);
+        io.atomix.primitive.partition.PartitionId atomixPartitionId =
+                io.atomix.primitive.partition.PartitionId.from(partitionGroup.name(), partitionId.id());
+        if (partitionGroup != null &&
+                partitionGroup.getPartition(atomixPartitionId) != null) {
+            partitionGroup.snapshot(atomixPartitionId).join();
+        }
+    }
 }