possible fix for #160 and maybe #154

.gitignore

@@ -154,3 +154,4 @@ distribution/
 #Roslyn compiler temp folders
 *.sln.ide/
 source/IdentityServer3.AccessTokenValidation.sln.GhostDoc.xml
+source/.vs/

default.ps1

@@ -10,7 +10,7 @@ properties {
 	$nuget_path = "$src_directory\.nuget\nuget.exe"
 
 	$buildNumber = 0;
-	$version = "2.15.0.0"
+	$version = "2.15.1.0"
 	$preRelease = $null
 }
 

source/AccessTokenValidation/AccessTokenValidation.csproj

@@ -89,6 +89,7 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="Plumbing\AdapterConfigurationManager.cs" />
     <Compile Include="Plumbing\IdentityServerOAuthBearerAuthenticationOptions.cs" />
     <Compile Include="IdentityServerBearerTokenAuthenticationOptions.cs" />
     <Compile Include="IdentityServerBearerTokenValidationAppBuilderExtensions.cs" />

source/AccessTokenValidation/Plumbing/AdapterConfigurationManager.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.IdentityModel.Protocols;
+
+namespace IdentityServer3.AccessTokenValidation.Plumbing
+{
+    internal class AdapterConfigurationManager : IConfigurationManager<OpenIdConnectConfiguration>
+    {
+        private readonly IConfigurationManager<OpenIdConnectConfiguration> _inner;
+
+        public AdapterConfigurationManager(IConfigurationManager<OpenIdConnectConfiguration> inner)
+        {
+            _inner = inner;
+        }
+
+        public Task<OpenIdConnectConfiguration> GetConfigurationAsync(CancellationToken cancel)
+        {
+            var res = AsyncHelper.RunSync(() => _inner.GetConfigurationAsync(cancel));
+            return Task.FromResult(res);
+        }
+
+        public void RequestRefresh()
+        {
+            return;
+        }
+    }
+}

source/AccessTokenValidation/Plumbing/DiscoveryDocumentIssuerSecurityTokenProvider.cs

@@ -23,13 +23,14 @@
 using System.Net.Http;
 using System.Security.Cryptography;
 using System.Threading;
+using IdentityServer3.AccessTokenValidation.Plumbing;
 
 namespace IdentityServer3.AccessTokenValidation
 {
     internal class DiscoveryDocumentIssuerSecurityTokenProvider : IIssuerSecurityTokenProvider
     {
         private readonly ReaderWriterLockSlim _synclock = new ReaderWriterLockSlim();
-        private readonly ConfigurationManager<OpenIdConnectConfiguration> _configurationManager;
+        private readonly IConfigurationManager<OpenIdConnectConfiguration> _configurationManager;
         private readonly ILogger _logger;
         private string _issuer;
         private IEnumerable<SecurityToken> _tokens;
@@ -51,10 +52,10 @@ public DiscoveryDocumentIssuerSecurityTokenProvider(string discoveryEndpoint, Id
                 webRequestHandler.ServerCertificateValidationCallback = options.BackchannelCertificateValidator.Validate;
             }
 
-            _configurationManager = new ConfigurationManager<OpenIdConnectConfiguration>(discoveryEndpoint, new HttpClient(handler))
+            _configurationManager = new AdapterConfigurationManager(new ConfigurationManager<OpenIdConnectConfiguration>(discoveryEndpoint, new HttpClient(handler))
             {
                 AutomaticRefreshInterval = options.AutomaticRefreshInterval
-            };
+            });
 
             if (!options.DelayLoadMetadata)
             {
@@ -134,7 +135,7 @@ private void RetrieveMetadata()
             _synclock.EnterWriteLock();
             try
             {
-                var result = AsyncHelper.RunSync(async () => await _configurationManager.GetConfigurationAsync());
+                var result = AsyncHelper.RunSync(async () => await _configurationManager.GetConfigurationAsync(CancellationToken.None));
 
                 if (result.JsonWebKeySet == null)
                 {