GraphQL multiple file upload returns NPE

[DimuthuMadushan]

Description:
consider the following service:

service /fileUpload on new graphql:Listener(9000) {
    remote function multipleFileUpload(graphql:Upload[] files) returns string[]|error {
        string[] fileInfo = [];
        foreach int i in 0..< files.length() {
            graphql:Upload file = files[i];
            check io:fileWriteBlocksFromStream(string`./files/${file.fileName}`, file.byteStream);
            fileInfo.push(file.fileName);
        }
        return fileInfo;
    }
}

This can be query as follow:

curl localhost:9000/fileUpload   
-F operations='{ "query": "mutation($file: [Upload!]!) { multipleFileUpload(files: $file) }", "variables": { "file": [null, null, null] } }'   
-F map='{ "0": ["file.0"], "1":["file.1"], "2":["file.2"]}' 
-F [email protected]
-F [email protected] 
-F [email protected]

Currently, this returns an NPE.