Add PublishedNodes field to ListVolumes Response

spec.md

@@ -1403,6 +1403,14 @@ message ListVolumesRequest {
 message ListVolumesResponse {
   message Entry {
     Volume volume = 1;
+
+    // A list of all `node_id` of nodes that the volume in this entry
+    // is controller published on.
+    // This is a REQUIRED field if the SP has the
+    // LIST_VOLUMES_PUBLISHED_NODES controller capability. If the SP
+    // does not have the LIST_VOLUMES_PUBLISHED_NODES capability this
+    // field MUST be empty.
+    repeated string published_nodes = 2;
   }
 
   repeated Entry entries = 1;
@@ -1515,6 +1523,10 @@ message ControllerServiceCapability {
 
       // See VolumeExpansion for details.
       EXPAND_VOLUME = 9;
+
+      // Indicates the SP supports the
+      // ListVolumesResponse.entry.published_nodes field
+      LIST_VOLUMES_PUBLISHED_NODES = 10;
     }
 
     Type type = 1;