Use var less in favor of final

example/cancel_request.dart

@@ -25,7 +25,7 @@ FutureOr<void> main(List<String> args) async {
     final helloRespFuture = client.get('hello');
 
     print('Sending async get /doesNotExist to ${uri.host}');
-    var ignoreThisFuture = client.send(cancelThisReq);
+    final ignoreThisFuture = client.send(cancelThisReq);
 
     print('Cancelling get /doesNotExist retries');
     client.cancel(cancelThisReq);

example/post_resource.dart

@@ -16,7 +16,7 @@ FutureOr<void> main(List<String> args) async {
   final uri = Uri(scheme: 'coap', host: 'coap.me', port: conf.defaultPort);
   final client = CoapClient(uri, conf);
 
-  var opt = CoapOption.createUriQuery(
+  final opt = CoapOption.createUriQuery(
       '${CoapLinkFormat.title}=This is an SJH Post request');
 
   try {

example/put_resource.dart

@@ -16,7 +16,7 @@ FutureOr<void> main(List<String> args) async {
   final uri = Uri(scheme: 'coap', host: 'coap.me', port: conf.defaultPort);
   final client = CoapClient(uri, conf);
 
-  var opt = CoapOption.createUriQuery(
+  final opt = CoapOption.createUriQuery(
       '${CoapLinkFormat.title}=This is an SJH Put request');
 
   try {

example/sync_vs_async.dart

@@ -45,7 +45,7 @@ FutureOr main() async {
 
     print('Sending 10 sync requests...');
     for (var i = 0; i < 10; i++) {
-      var resp = await client.get('test');
+      final resp = await client.get('test');
       if (resp.code != CoapCode.content) {
         print('Request failed!');
       }

lib/src/coap_media_type.dart

@@ -288,8 +288,7 @@ class CoapMediaType {
       return null;
     }
     final res = <int>[];
-    var regex1 = regex.trim().substring(0, regex.indexOf('*')).trim();
-    regex1 += '.*';
+    final regex1 = regex.substring(0, regex.indexOf('*')).trim() + '.*';
     final r = RegExp(regex1);
     _registry.forEach((int key, List<String> value) {
       final mime = value[0];

lib/src/coap_message.dart

@@ -540,9 +540,9 @@ class CoapMessage {
 
   /// URI path
   String get uriPath {
-    var join = CoapOption.join(
+    final join = CoapOption.join(
         getOptions(optionTypeUriPath) as List<CoapOption>?, '/')!;
-    return join += '/';
+    return join + '/';
   }
 
   /// Sets a number of Uri path options from a string, ignores any trailing / character

lib/src/coap_option.dart

@@ -179,8 +179,7 @@ class CoapOption {
   @override
   int get hashCode {
     const prime = 31;
-    var result = 1;
-    return result = prime * result + _type;
+    return prime + _type;
   }
 
   @override
@@ -268,22 +267,17 @@ class CoapOption {
 
   /// Joins the string values of a set of options.
   static String? join(List<CoapOption>? options, String delimiter) {
-    String? s;
     if (null == options) {
-      return s;
-    } else {
-      final sb = StringBuffer();
-      var append = false;
-      for (final opt in options) {
-        if (append) {
-          sb.write(delimiter);
-        } else {
-          append = true;
-        }
-        sb.write(opt.stringValue);
+      return null;
+    }
+    final sb = StringBuffer();
+    for (final opt in options) {
+      if (opt != options.first) {
+        sb.write(delimiter);
       }
-      return sb.toString();
+      sb.write(opt.stringValue);
     }
+    return sb.toString();
   }
 
   /// Returns a string representation of the option type.

lib/src/endpoint/resources/coap_endpoint_resource.dart

@@ -112,19 +112,14 @@ abstract class CoapEndpointResource {
 
   /// Gets the URI of this resource.
   String get path {
-    var sb = StringBuffer();
-    sb.write(name);
     if (_parent == null) {
-      sb.write('/');
-    } else {
-      var res = _parent;
-      while (res != null) {
-        final tmp = StringBuffer('${res.name}/${sb.toString()}');
-        sb = tmp;
-        res = res._parent;
-      }
+      return '/$name';
+    }
+    var names = [name];
+    for (var res = _parent; res != null; res = res._parent) {
+      names.add(res.name);
     }
-    return sb.toString();
+    return names.reversed.join('/');
   }
 
   /// Attributes

lib/src/net/coap_matcher.dart

@@ -294,7 +294,7 @@ class CoapMatcher implements CoapIMatcher {
   void _removeNotificatoinsOf(CoapObserveRelation relation) {
     for (final previous in relation.clearNotifications()) {
       // Notifications are local MID namespace
-      var keyId = CoapKeyId(previous!.id);
+      final keyId = CoapKeyId(previous!.id);
       _exchangesById.remove(keyId);
     }
   }

test/coap_base_class_test.dart

@@ -28,7 +28,7 @@ void main() {
     test('Negotiation Content', () {
       const defaultContentType = 10;
       final supported = <int>[11, 5];
-      var accepted = <CoapOption>[];
+      final accepted = <CoapOption>[];
       final opt1 = CoapOption.createVal(optionTypeMaxAge, 10);
       final opt2 = CoapOption.createVal(optionTypeContentFormat, 5);
       accepted.add(opt1);