Added support for "maps" cli command that displays meta information for various consistent maps in the system

Change-Id: I63e590a8520ac9d1238efe4ad0033dcba939e472
diff --git a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/PartitionedDatabase.java b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/PartitionedDatabase.java
index cb4ddfc..ad049e6 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/PartitionedDatabase.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/PartitionedDatabase.java
@@ -78,6 +78,17 @@
     }
 
     @Override
+    public CompletableFuture<Set<String>> tableNames() {
+        checkState(isOpen.get(), DB_NOT_OPEN);
+        Set<String> tableNames = Sets.newConcurrentHashSet();
+        return CompletableFuture.allOf(partitions
+                .stream()
+                .map(db -> db.tableNames().thenApply(tableNames::addAll))
+                .toArray(CompletableFuture[]::new))
+            .thenApply(v -> tableNames);
+    }
+
+    @Override
     public CompletableFuture<Integer> size(String tableName) {
         checkState(isOpen.get(), DB_NOT_OPEN);
         AtomicInteger totalSize = new AtomicInteger(0);