code: public CMAAssetFile setUploadFrom(CMALink uploadFrom) {
      this.uploadFrom = uploadFrom;
      this.upload = null;
      this.url = null;
      this.details = null;
      return this;
    }
docs: Set a link to a Contentful Upload entry, to be used for processing the binary data from.
  <p>
  Warning: Setting an upload from will also erase the {@link #url}, {@link #details} and
  {@link #upload}, until the asset got processed again.
  
  @param uploadFrom a link to an uploaded resource.
  @return the calling instance for chaining.
  @see com.contentful.java.cma.ModuleUploads