Added LastOperationResource.RetryAfter

src/Model/LastOperationResource.cs

@@ -16,6 +16,13 @@ public class LastOperationResource : StatusBase, IEquatable<LastOperationResourc
     [JsonConverter(typeof(StringEnumConverter))]
     public LastOperationResourceState State { get; set; }
 
+    /// <summary>
+    /// Indicates how long the platform should wait before polling again.
+    /// Only used on server-side. See <c>LastOperationEndpoint.PollingInterval</c> instead on client-side.
+    /// </summary>
+    [JsonIgnore]
+    public TimeSpan? RetryAfter { get; set; }
+
     public bool Equals(LastOperationResource other)
         => other != null
         && base.Equals(other)

src/Server/Bindings/ServiceBindingsController.cs

@@ -139,7 +139,12 @@ public Task<IActionResult> GetLastOperation(
         var context = Context(instanceId, bindingId);
         return Do(acceptsIncomplete: true,
             blocking: _ => throw new NotSupportedException("This server does not support asynchronous operations."),
-            deferred: async x => Ok(await x.GetLastOperationAsync(context, serviceId, planId, operation)));
+            deferred: async x =>
+            {
+                var resource = await x.GetLastOperationAsync(context, serviceId, planId, operation);
+                if (resource.RetryAfter is { } retryAfter) SetRetryAfter(retryAfter);
+                return Ok(resource);
+            });
     }
 
     private ServiceBindingContext Context(string instanceId, string bindingId)

src/Server/BrokerControllerBase.cs

@@ -1,3 +1,4 @@
+using System.Globalization;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.DependencyInjection;
 using OpenServiceBroker.Errors;
@@ -98,4 +99,12 @@ protected OriginatingIdentity? OriginatingIdentity
             return string.IsNullOrEmpty(headerValue) ? null : OriginatingIdentity.Parse(headerValue);
         }
     }
+
+    /// <summary>
+    /// Sets the Retry-After response header.
+    /// </summary>
+    protected void SetRetryAfter(TimeSpan retryAfter)
+    {
+        HttpContext.Response.Headers.RetryAfter = retryAfter.TotalSeconds.ToString("0", CultureInfo.InvariantCulture);
+    }
 }

src/Server/Instances/ServiceInstancesController.cs

@@ -168,7 +168,12 @@ public Task<IActionResult> GetLastOperation(
         var context = Context(instanceId);
         return Do(acceptsIncomplete: true,
             blocking: _ => throw new NotSupportedException("This server does not support asynchronous operations."),
-            deferred: async x => Ok(await x.GetLastOperationAsync(context, serviceId, planId, operation)));
+            deferred: async x =>
+            {
+                var resource = await x.GetLastOperationAsync(context, serviceId, planId, operation);
+                if (resource.RetryAfter is { } retryAfter) SetRetryAfter(retryAfter);
+                return Ok(resource);
+            });
     }
 
     private ServiceInstanceContext Context(string? instanceId)

src/UnitTests/Bindings/ServiceBindingDeferredFacts.cs

@@ -129,13 +129,16 @@ public async Task GetLastOperation()
     {
         var response = new LastOperationResource
         {
-            State = LastOperationResourceState.InProgress
+            State = LastOperationResourceState.InProgress,
+            RetryAfter = TimeSpan.FromSeconds(5)
         };
-
         Mock.Setup(x => x.GetLastOperationAsync(new("123", "456"), "abc", "xyz", "my operation"))
             .ReturnsAsync(response);
-        var result = await Client.ServiceInstancesDeferred["123"].ServiceBindings["456"].LastOperation("abc", "xyz", "my operation").ReadAsync();
+
+        var endpoint = Client.ServiceInstancesDeferred["123"].ServiceBindings["456"].LastOperation("abc", "xyz", "my operation");
+        var result = await endpoint.ReadAsync();
         result.Should().BeEquivalentTo(response);
+        endpoint.PollingInterval.Should().Be(TimeSpan.FromSeconds(5));
     }
 
     [Fact]