fixup! Implement ExposedThing functionality

example/exposed_thing/http_server.dart

@@ -14,7 +14,13 @@ String property = "hi :)";
 void main() async {
   final servient = Servient.create(
     clientFactories: [HttpClientFactory()],
-    servers: [HttpServer(HttpConfig(port: 3000))],
+    servers: [
+      HttpServer(
+        HttpConfig(
+          port: 3000,
+        ),
+      ),
+    ],
   );
 
   final wot = await servient.start();

lib/src/binding_http/http_config.dart

@@ -4,16 +4,28 @@
 //
 // SPDX-License-Identifier: BSD-3-Clause
 
+import "dart:io";
+
 /// Allows for configuring the behavior of HTTP clients and servers.
 class HttpConfig {
   /// Creates a new [HttpConfig] object.
-  HttpConfig({this.port, this.secure});
+  HttpConfig({
+    int? port,
+    this.secure = false,
+    InternetAddress? bindAddress,
+  })  : port = port ?? (secure ? 443 : 80),
+        bindAddress = bindAddress ?? InternetAddress.anyIPv4;
 
   /// Custom port number that should be used by a server.
   ///
   /// Defaults to 80 for HTTP and 443 for HTTPS.
-  int? port;
+  final int port;
 
   /// Indicates if the client or server should use HTTPS.
-  bool? secure;
+  bool secure;
+
+  /// The IP address the HTTP server should bind to.
+  ///
+  /// Defaults to [InternetAddress.anyIPv4].
+  final InternetAddress bindAddress;
 }

lib/src/binding_http/http_server.dart

@@ -21,16 +21,17 @@ final class HttpServer implements ProtocolServer {
   HttpServer(HttpConfig? httpConfig)
       // TODO(JKRhb): Check if the scheme should be determined differently.
       : scheme = httpConfig?.secure ?? false ? "https" : "http",
-        port = _portFromConfig(httpConfig);
+        port = _portFromConfig(httpConfig),
+        bindAddress = httpConfig?.bindAddress ?? io.InternetAddress.anyIPv4;
 
   @override
   final String scheme;
 
   @override
   final int port;
 
-  // FIXME
-  final Object _bindAddress = io.InternetAddress.loopbackIPv4;
+  /// The [io.InternetAddress] this server is bound to.
+  final io.InternetAddress bindAddress;
 
   io.HttpServer? _server;
 
@@ -219,7 +220,7 @@ final class HttpServer implements ProtocolServer {
       throw StateError("Server already started");
     }
 
-    _server = await shelf_io.serve(_handleRequest, _bindAddress, port);
+    _server = await shelf_io.serve(_handleRequest, bindAddress, port);
 
     _servient = servient;
   }