Add HubSpot to the list of supported providers

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationHandlers.cs

@@ -426,6 +426,14 @@ public static partial class OpenIddictClientWebIntegrationHandlers
 
             context.UserinfoEndpoint = context.Registration.ProviderName switch
             {
+                // HubSpot doesn't have a static userinfo endpoint but allows retrieving basic information
+                // by using an access token info endpoint that requires sending the token in the URI path.
+                Providers.HubSpot when
+                    (context.BackchannelAccessToken ?? context.FrontchannelAccessToken) is { Length: > 0 } token
+                    => OpenIddictHelpers.CreateAbsoluteUri(
+                        left : new Uri("https://api.hubapi.com/oauth/v1/access-tokens", UriKind.Absolute),
+                        right: new Uri(token, UriKind.Relative)),
+
                 // SuperOffice doesn't expose a static OpenID Connect userinfo endpoint but offers an API whose
                 // absolute URI needs to be computed based on a special claim returned in the identity token.
                 Providers.SuperOffice when

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationProviders.xml

@@ -308,6 +308,31 @@
              Description="The value used as the 'access_type' parameter (can be set to 'offline' to retrieve a refresh token)" />
   </Provider>
 
+  <!--
+                                        ▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄
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+  -->
+
+  <Provider Name="HubSpot" Documentation="https://developers.hubspot.com/docs/api/oauth-quickstart-guide">
+    <Environment Issuer="https://www.hubspot.com/">
+      <Configuration AuthorizationEndpoint="https://app.hubspot.com/oauth/authorize"
+                     TokenEndpoint="https://api.hubapi.com/oauth/v1/token">
+        <GrantType Value="authorization_code" />
+        <GrantType Value="refresh_token" />
+      </Configuration>
+
+      <!--
+        Note: HubSpot requires sending the "profile" scope to
+        be able to use the dynamic access token info endpoint.
+      -->
+
+      <Scope Name="oauth" Default="true" Required="true" />
+    </Environment>
+  </Provider>
+
   <!--
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