Support for FirstAcquirer field

src/ArtemisNetClient/Message/Header.cs

@@ -46,5 +46,7 @@ public uint? Ttl
         }
 
         public uint DeliveryCount => _innerHeader.HasField(4) ? _innerHeader.DeliveryCount : default;
+
+        public bool FirstAcquirer => _innerHeader.FirstAcquirer;
     }
 }

src/ArtemisNetClient/Message/Message.cs

@@ -150,6 +150,12 @@ public byte[] UserId
         /// </summary>
         public uint DeliveryCount => Header.DeliveryCount;
 
+        /// <summary>
+        /// If this value is true, then this message has not been acquired by any other link.
+        /// If this value is false, then this message MAY have previously been acquired by another link or links.
+        /// </summary>
+        public bool FirstAcquirer => Header.FirstAcquirer;
+
         public DurabilityMode? DurabilityMode
         {
             get => Header.Durable switch

test/ArtemisNetClient.IntegrationTests/MessageFirstAcquirerSpec.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Threading.Tasks;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace ActiveMQ.Artemis.Client.IntegrationTests
+{
+    public class MessageFirstAcquirerSpec : ActiveMQNetIntegrationSpec
+    {
+        public MessageFirstAcquirerSpec(ITestOutputHelper output) : base(output)
+        {
+        }
+
+        [Fact]
+        public async Task Should_receive_msg_with_FirstAcquirer_set_when_msg_was_received_for_the_first_time()
+        {
+            await using var connection = await CreateConnection();
+            var address = Guid.NewGuid().ToString();
+            await using var producer = await connection.CreateProducerAsync(address, RoutingType.Anycast);
+            await using var consumer1 = await connection.CreateConsumerAsync(address, RoutingType.Anycast);
+            await using var consumer2 = await connection.CreateConsumerAsync(address, RoutingType.Anycast);
+
+            await producer.SendAsync(new Message("foo"));
+            var msg = await consumer1.ReceiveAsync(CancellationToken);
+            Assert.True(msg.FirstAcquirer);
+        }
+
+        [Fact]
+        public async Task Should_receive_msg_with_FirstAcquirer_set_to_false_when_msg_was_redelivered()
+        {
+            await using var connection = await CreateConnection();
+            var address = Guid.NewGuid().ToString();
+            await using var producer = await connection.CreateProducerAsync(address, RoutingType.Anycast);
+            await using var consumer1 = await connection.CreateConsumerAsync(address, RoutingType.Anycast);
+            await using var consumer2 = await connection.CreateConsumerAsync(address, RoutingType.Anycast);
+
+            await producer.SendAsync(new Message("foo"));
+            var msg = await consumer1.ReceiveAsync(CancellationToken);
+            consumer1.Reject(msg);
+
+            var msg2 = await consumer2.ReceiveAsync(CancellationToken);
+            Assert.False(msg2.FirstAcquirer);
+        }
+    }
+}