Fix conflict if paramName is data

modules/openapi-generator/src/main/resources/dart-dio/api.mustache

@@ -51,14 +51,14 @@ class {{classname}} {
             {{^isListContainer}}
             var serializedBody = _serializers.serialize({{paramName}});
             {{/isListContainer}}
-            var data = json.encode(serializedBody);
+            var json{{paramName}} = json.encode(serializedBody);
         {{/bodyParam}}
 
             return _dio.request(
             path,
             queryParameters: queryParams,
         {{#bodyParam}}
-                data: data,
+                data: json{{paramName}},
         {{/bodyParam}}
             options: Options(
             method: '{{httpMethod}}'.toUpperCase(),

samples/client/petstore/dart-dio/lib/api.dart

@@ -8,45 +8,52 @@ import 'package:openapi/api/pet_api.dart';
 import 'package:openapi/api/store_api.dart';
 import 'package:openapi/api/user_api.dart';
 
+
 class Openapi {
-  Dio dio;
-  Serializers serializers;
-  String basePath = "http://petstore.swagger.io/v2";
 
-  Openapi({this.dio, Serializers serializers}) {
+    Dio dio;
+    Serializers serializers;
+    String basePath = "http://petstore.swagger.io/v2";
+
+    Openapi({this.dio, Serializers serializers}) {
     if (dio == null) {
-      BaseOptions options = new BaseOptions(
-        baseUrl: basePath,
-        connectTimeout: 5000,
-        receiveTimeout: 3000,
-      );
-      this.dio = new Dio(options);
+        BaseOptions options = new BaseOptions(
+            baseUrl: basePath,
+            connectTimeout: 5000,
+            receiveTimeout: 3000,
+        );
+        this.dio = new Dio(options);
     }
 
     this.serializers = serializers ?? standardSerializers;
-  }
+}
 
-  /**
+
+    /**
     * Get PetApi instance, base route and serializer can be overridden by a given but be careful,
     * by doing that all interceptors will not be executed
     */
-  PetApi getPetApi() {
+    PetApi getPetApi() {
     return PetApi(dio, serializers);
-  }
+    }
+
 
-  /**
+    /**
     * Get StoreApi instance, base route and serializer can be overridden by a given but be careful,
     * by doing that all interceptors will not be executed
     */
-  StoreApi getStoreApi() {
+    StoreApi getStoreApi() {
     return StoreApi(dio, serializers);
-  }
+    }
+
 
-  /**
+    /**
     * Get UserApi instance, base route and serializer can be overridden by a given but be careful,
     * by doing that all interceptors will not be executed
     */
-  UserApi getUserApi() {
+    UserApi getUserApi() {
     return UserApi(dio, serializers);
-  }
-}
+    }
+
+
+}