My headers are set in constructor as follow:
this.headers = new Headers();
this.headers.append('Content-Type', 'multipart/form-data;boundary=--boundary');
I have collected data to post it out in formData
.....
let data = new FormData();
data.append('file', file);
data.append('fileName', file.name);
data.append('fileSize', file.size.toString());
data.append('fileType', file.type);
data.append('fileLastMod', file.lastModifiedDate);
.....
Here i am posting the data
let url = 'http://api.********.com/gallery/'+ this.selectedCategory;
this._http.post(url, data, {headers : this.headers})
.toPromise()
.catch(reason => {
console.log(JSON.stringify(reason));
}).then(result => {
console.log('From Promise:', result);
});
But i get following error:

API that i am approaching requires following:

So my question is how to set up these requirements like boundaries, content disposition an so on ? These are pretty new things to me.
headers.set('Accept', 'application/json');