title: How to upload files with graphql-java?
body: <p>I can't find out how to upload files if i use graphql-java, can someone show me a demo? I will be appreciated!</p>
  
  <p>reference :  <a href="https://github.com/graphql-java-kickstart/graphql-java-tools/issues/240" rel="nofollow noreferrer">https://github.com/graphql-java-kickstart/graphql-java-tools/issues/240</a></p>
  
  <p>I tried it in springboot by using graphql-java-kickstart graphql-java-tools, but it didn't work</p>
  
  <pre><code>@Component
  public class FilesUpload implements GraphQLMutationResolver {
  
      public Boolean testMultiFilesUpload(List&lt;Part&gt; parts, DataFetchingEnvironment env) {
          // get file parts from DataFetchingEnvironment, the parts parameter is not used
          List&lt;Part&gt; attchmentParts = env.getArgument("files");
          System.out.println(attchmentParts);
          return true;
      }
  }
  </code></pre>
  
  <p>this is my schema</p>
  
  <pre><code>type Mutation {
      testSingleFileUpload(file: Upload): UploadResult
  }
  </code></pre>
  
  <p>I expect this resolver can print attchmentParts,so i can get the file part.</p>