ethclient: omit nil address/topics from filter args (#33464)

Fixes #33369

This omits "topics" and "addresses" from the filter when they are unspecified.
It is required for interoperability with some server implementations that cannot
handle `null` for these fields.

ethclient/ethclient.go

@@ -497,9 +497,12 @@ func (ec *Client) SubscribeFilterLogs(ctx context.Context, q ethereum.FilterQuer
 }
 
 func toFilterArg(q ethereum.FilterQuery) (interface{}, error) {
-	arg := map[string]interface{}{
-		"address": q.Addresses,
-		"topics":  q.Topics,
+	arg := map[string]interface{}{}
+	if q.Addresses != nil {
+		arg["address"] = q.Addresses
+	}
+	if q.Topics != nil {
+		arg["topics"] = q.Topics
 	}
 	if q.BlockHash != nil {
 		arg["blockHash"] = *q.BlockHash

ethclient/types_test.go

@@ -41,6 +41,18 @@ func TestToFilterArg(t *testing.T) {
 		output interface{}
 		err    error
 	}{
+		{
+			"without addresses",
+			ethereum.FilterQuery{
+				FromBlock: big.NewInt(1),
+				ToBlock:   big.NewInt(2),
+			},
+			map[string]interface{}{
+				"fromBlock": "0x1",
+				"toBlock":   "0x2",
+			},
+			nil,
+		},
 		{
 			"without BlockHash",
 			ethereum.FilterQuery{