dont put wantlist getter in exchange interface

core/commands/bitswap.go

@@ -33,8 +33,13 @@ Print out all blocks currently on the bitswap wantlist for the local peer`,
 			res.SetError(err, cmds.ErrNormal)
 			return
 		}
+		bs, ok := nd.Exchange.(*bitswap.Bitswap)
+		if !ok {
+			res.SetError(u.ErrCast(), cmds.ErrNormal)
+			return
+		}
 
-		res.SetOutput(&KeyList{nd.Exchange.GetWantlist()})
+		res.SetOutput(&KeyList{bs.GetWantlist()})
 	},
 	Marshalers: cmds.MarshalerMap{
 		cmds.Text: KeyListTextMarshaler,

exchange/interface.go

@@ -21,7 +21,5 @@ type Interface interface {
 	// available on the network?
 	HasBlock(context.Context, *blocks.Block) error
 
-	GetWantlist() []u.Key
-
 	io.Closer
 }

exchange/offline/offline.go

@@ -66,8 +66,3 @@ func (e *offlineExchange) GetBlocks(ctx context.Context, ks []u.Key) (<-chan *bl
 	}()
 	return out, nil
 }
-
-// implement Exchange
-func (e *offlineExchange) GetWantlist() []u.Key {
-	return nil
-}