Implemented the Get All Users In A Role method

Author: Alan Quillin

src/corelib/Providers/Rackspace/CloudIdentityProvider.cs

@@ -131,6 +131,16 @@ public IEnumerable<Role> ListRoles(string serviceId = null, string markerId = nu
             return provider.ListRoles(serviceId, markerId, limit, identity);
         }
 
+        /// <inheritdoc/>
+        public IEnumerable<User> ListUsersByRole(string roleId, bool? enabled = null, string markerId = null, int? limit = null, CloudIdentity identity = null)
+        {
+            if (limit < 0 || limit > 1000)
+                throw new ArgumentOutOfRangeException("limit");
+
+            var provider = GetProvider(identity);
+            return provider.ListUsersByRole(roleId, enabled, markerId, limit, identity);
+        }
+
         /// <inheritdoc/>
         public Role AddRole(string name, string description, CloudIdentity identity)
         {

src/corelib/Providers/Rackspace/GeographicalCloudIdentityProvider.cs

@@ -155,6 +155,41 @@ public bool DeleteRoleFromUser(string userId, string roleId, CloudIdentity ident
             return false;
         }
 
+        /// <inheritdoc/>
+        public IEnumerable<User> ListUsersByRole(string roleId, bool? enabled = null, string markerId = null, int? limit = null, CloudIdentity identity = null)
+        {
+            if (limit < 0 || limit > 1000)
+                throw new ArgumentOutOfRangeException("limit");
+
+            CheckIdentity(identity);
+
+            var parameters = BuildOptionalParameterList(new Dictionary<string, string>
+                {
+                    {"enabled", !enabled.HasValue ? null : enabled.Value ? "true" : "false"},
+                    {"marker", markerId},
+                    {"limit", !limit.HasValue ? null : limit.Value.ToString()},
+                });
+
+            var urlPath = string.Format("/v2.0/OS-KSADM/roles/{0}/RAX-AUTH/users", roleId);
+            var response = ExecuteRESTRequest<UsersResponse>(identity, urlPath, HttpMethod.GET, queryStringParameter: parameters);
+
+            if (response == null || response.Data == null)
+                return null;
+            // Due to the fact the sometimes the API returns a JSON array of users and sometimes it returns a single JSON user object.  
+            // Therefore if we get a null data object (which indicates that the deserializer could not parse to an array) we need to try and parse as a single User object.
+            if (response.Data.Users == null)
+            {
+                var userResponse = JsonConvert.DeserializeObject<UserResponse>(response.RawBody);
+
+                if (response == null || response.Data == null)
+                    return null;
+
+                return new[] { userResponse.User };
+            }
+
+            return response.Data.Users;
+        }
+
         #endregion
 
         #region Credentials

src/corelib/Providers/Rackspace/IExtendedCloudIdentityProvider.cs

@@ -30,6 +30,22 @@ public interface IExtendedCloudIdentityProvider : IIdentityProvider
         /// <seealso href="http://docs.rackspace.com/openstack-extensions/auth/OS-KSADM-admin-devguide/content/GET_listRoles_v2.0_OS-KSADM_roles_Admin_API_Service_Developer_Operations-d1e1357.html">List Roles (Rackspace OS-KSADM Extension - API v2.0)</seealso>
         IEnumerable<Role> ListRoles(string serviceId = null, string markerId = null, int? limit = null, CloudIdentity identity = null);
 
+        /// <summary>
+        /// Lists all roles.
+        /// <note type="warning">The behavior of this API method is not defined. Do not use.</note>
+        /// </summary>
+        /// <param name="roleId">The role ID. The behavior is unspecified if this is not obtained from <see cref="Role.Id"/>.</param>
+        /// <param name="enabled">Allows you to filter enabled or un-enabled users. If the value is <c>null</c>, a provider-specific default value is used.</param>
+        /// <param name="markerId">The <see cref="Role.Id"/> of the last item in the previous list. Used for pagination. If the value is <c>null</c>, the list starts at the beginning.</param>
+        /// <param name="limit">Indicates the maximum number of items to return. Used for pagination. If the value is <c>null</c>, a provider-specific default value is used.</param>
+        /// <param name="identity">The cloud identity to use for this request. If not specified, the default identity for the current provider instance will be used.</param>
+        /// <returns>A collection of <see cref="Role"/> objects describing the requested roles.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">If <paramref name="limit"/> is less than 0 or greater than 1000.</exception>
+        /// <exception cref="NotSupportedException">If the provider does not support the given <paramref name="identity"/> type.</exception>
+        /// <exception cref="InvalidOperationException">If <paramref name="identity"/> is <c>null</c> and no default identity is available for the provider.</exception>
+        /// <exception cref="ResponseException">If the REST API request failed.</exception>
+        IEnumerable<User> ListUsersByRole(string roleId, bool? enabled = null, string markerId = null, int? limit = null, CloudIdentity identity = null);
+
         /// <summary>
         /// Create a new role.
         /// </summary>