don't always use TCP first

Signed-off-by: zirain <zirain2009@gmail.com>

Author: zirain

internal/gatewayapi/validate.go

@@ -1020,9 +1020,31 @@ func markProtocolConflicts(portListenerInfo map[gwapiv1.PortNumber]*portListener
 					}
 				}
 			default:
-				// All from ListenerSet: first TCP listener wins
+				// All from ListenerSet: use deterministic first-listener precedence.
+				// Listeners that do not match the first listener's protocol are conflicted.
+				var winnerProtocol string
+				for _, listener := range info.listeners {
+					// UDP does not participate in protocol conflict checks.
+					if listener.Protocol == gwapiv1.UDPProtocolType {
+						continue
+					}
+					winnerProtocol = getProtocolForListener(listener)
+					break
+				}
+				if winnerProtocol == "" {
+					continue
+				}
 				for _, listener := range layer4Listeners {
-					setProtocolConflictConditions(listener)
+					if getProtocolForListener(listener) != winnerProtocol {
+						setProtocolConflictConditions(listener)
+					}
+				}
+				for _, listeners := range hostnameGroups {
+					for _, listener := range listeners {
+						if getProtocolForListener(listener) != winnerProtocol {
+							setProtocolConflictConditions(listener)
+						}
+					}
 				}
 			}
 		} else if len(layer4Listeners) > 1 {