From 9878ef926db2fb45d33a9331feff1e38221ad267 Mon Sep 17 00:00:00 2001
From: locoholy <68823405+locoholy@users.noreply.github.com>
Date: Tue, 7 Apr 2026 21:01:26 +0500
Subject: [PATCH] ethclient: omit empty address/topics fields in RPC filter
 requests (#33884)

Changes JSON serialization of FilterCriteria to exclude "address" when it is empty.
---
 ethclient/ethclient.go  |  6 +++++-
 ethclient/types_test.go | 16 ++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/ethclient/ethclient.go b/ethclient/ethclient.go
index 85286ec919..412f8955ba 100644
--- a/ethclient/ethclient.go
+++ b/ethclient/ethclient.go
@@ -498,7 +498,11 @@ func (ec *Client) SubscribeFilterLogs(ctx context.Context, q ethereum.FilterQuer
 
 func toFilterArg(q ethereum.FilterQuery) (interface{}, error) {
 	arg := map[string]interface{}{}
-	if q.Addresses != nil {
+	// Only include "address" when there are actual address filters.
+	// An empty slice is treated the same as nil (no filter), and omitting
+	// the field avoids sending "address":[] to nodes that reject empty arrays
+	// (e.g. Hedera, some non-Geth implementations).
+	if len(q.Addresses) > 0 {
 		arg["address"] = q.Addresses
 	}
 	if q.Topics != nil {
diff --git a/ethclient/types_test.go b/ethclient/types_test.go
index dcb9a579b7..8820b11162 100644
--- a/ethclient/types_test.go
+++ b/ethclient/types_test.go
@@ -53,6 +53,22 @@ func TestToFilterArg(t *testing.T) {
 			},
 			nil,
 		},
+		{
+			// empty Addresses slice must be treated same as nil:
+			// the "address" field must be omitted so that non-Geth nodes
+			// (e.g. Hedera) do not reject the request with an error.
+			"with empty addresses slice",
+			ethereum.FilterQuery{
+				Addresses: []common.Address{},
+				FromBlock: big.NewInt(1),
+				ToBlock:   big.NewInt(2),
+			},
+			map[string]interface{}{
+				"fromBlock": "0x1",
+				"toBlock":   "0x2",
+			},
+			nil,
+		},
 		{
 			"without BlockHash",
 			ethereum.FilterQuery{