code: public CMAAssetFile setUploadUrl(String upload) {
      this.upload = upload;
      this.url = null;
      this.uploadFrom = null;
      this.details = null;
      return this;
    }
docs: Set a public accessible url to be used for processing the binary data from.
  <p>
  Warning: Setting an upload url will also erase the {@link #url}, {@link #details} and
  {@link #uploadFrom}, until the asset got processed again.
  
  @param upload the remote url of the upload.
  @return the calling instance for chaining.