title: Static members from supertypes must be qualified by the name of the defining type
body: <p>I am creating some classes and I am getting this issue: Static members from supertypes must be qualified by the name of the defining type.
  post(Documnet document) ->Future</p>
  
  <p>My clases are these:</p>
  
  <p>UserApi</p>
  
  <pre><code>import '../api-helper.dart';
  import '../../graphql/documents/login.dart';
  import 'dart:async';
  
  class UserAPI extends APIHelper {
  
    static Future&lt;dynamic&gt; login(account) async {
      return await post(new Login('name', 'email', 'token', 'refreshToken', 'createdAt', 'expiresAt', false));
    }
  
  }
  </code></pre>
  
  <p>APIHelper</p>
  
  <pre><code>import 'package:graphql_flutter/graphql_flutter.dart' show Client, InMemoryCache;
  import '../graphql/document.dart';
  import '../graphql/graphql-helper.dart';
  import 'dart:async';
  
  class APIHelper {
  
    static const GRAPHQL_URL = 'https://heat-map-api.herokuapp.com/graphql';
    static final _client = Client(
        endPoint: GRAPHQL_URL,
        cache: new InMemoryCache(),
      );
  
    static Future&lt;dynamic&gt; post(Document document) async {
      return await _client.query(query: GraphQLHelper.getBodyMutation(document), variables: GraphQLHelper.getVariables(document));
    }
  
  }
  </code></pre>
  
  <p>What should I do in order to fix this? I don't have compiled the project yet, but it scares me.</p>