Add remote address information in SessionProtocolNegotiationException

core/src/main/java/com/linecorp/armeria/client/HttpChannelPool.java

@@ -356,7 +356,9 @@ private void connect(SessionProtocol desiredProtocol, SerializationFormat serial
             notifyConnect(desiredProtocol, key,
                           eventLoop.newFailedFuture(
                                   new SessionProtocolNegotiationException(
-                                          desiredProtocol, "previously failed negotiation")),
+                                          desiredProtocol,
+                                          "previously failed negotiation (remoteAddress: " +
+                                          remoteAddress + ")")),
                           promise, timingsBuilder);
             return;
         }

core/src/main/java/com/linecorp/armeria/client/HttpClientPipelineConfigurator.java

@@ -461,7 +461,8 @@ void finishWithNegotiationFailure(
         final ChannelPipeline pipeline = ctx.pipeline();
         pipeline.channel().eventLoop().execute(
                 () -> pipeline.fireUserEventTriggered(
-                        new SessionProtocolNegotiationException(expected, actual, reason)));
+                        new SessionProtocolNegotiationException(
+                                expected, actual, reason + " (channel: " + pipeline.channel() + ")")));
         ctx.close();
     }
 

core/src/main/java/com/linecorp/armeria/client/HttpSessionHandler.java

@@ -174,7 +174,7 @@ private void scheduleSessionTimeout(Channel channel, Promise<Channel> sessionPro
         sessionTimeoutFuture = channel.eventLoop().schedule(() -> {
             if (sessionPromise.tryFailure(new SessionProtocolNegotiationException(
                     desiredProtocol,
-                    "connection established, but session creation timed out: " + channel))) {
+                    "connection established, but session creation timed out. (channel: " + channel + ")"))) {
                 channel.close();
             }
         }, connectionTimeoutMillis, TimeUnit.MILLISECONDS);

core/src/test/java/com/linecorp/armeria/client/H2WithoutAlpnTest.java

@@ -101,8 +101,12 @@ void shouldRejectH2WithoutAlpn() {
             assertThatThrownBy(() -> client.get("/"))
                     .isInstanceOf(UnprocessedRequestException.class)
                     .hasCauseInstanceOf(SessionProtocolNegotiationException.class)
-                    .hasMessageContaining("expected: h2, actual: h1, " +
-                                          "reason: unexpected protocol negotiation result");
+                    .hasMessageContainingAll(
+                            "expected: h2",
+                            "actual: h1",
+                            "reason: unexpected protocol negotiation result",
+                            "R:127.0.0.1"
+                    );
         }
     }
 }