diff --git a/common/src/test/java/bisq/HashMapOrderTest.java b/common/src/test/java/bisq/HashMapOrderTest.java
new file mode 100644
index 00000000000..1755eff4f63
--- /dev/null
+++ b/common/src/test/java/bisq/HashMapOrderTest.java
@@ -0,0 +1,28 @@
+package bisq;
+
+import java.util.TreeMap;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertArrayEquals;
+
+
+
+import protobuf.TempProposalPayload;
+
+public class HashMapOrderTest {
+    @Test
+    public void mapIsNotOrderPreservingButAlwaysEnforcesKeyOrder() {
+        TreeMap<String, String> order1 = new TreeMap<>();
+        order1.put("k1", "v1");
+        order1.put("k2", "v2");
+        TreeMap<String, String> order2 = new TreeMap<>();
+        order2.put("k2", "v2");
+        order2.put("k1", "v1");
+        TempProposalPayload prop = TempProposalPayload.newBuilder().putAllExtraData(order1).build();
+        byte[] bytes1 = prop.toByteArray();
+        TempProposalPayload prop2 = TempProposalPayload.newBuilder().putAllExtraData(order2).build();
+        byte[] bytes2 = prop2.toByteArray();
+        assertArrayEquals(bytes1, bytes2);
+    }
+}