Is there any way to find out from the downloads DataSource if the DataSpec represents a decryption key?

When downloading an HLS stream, I would like to apply a ResolvingDataSource to change the uri on the DataSpec, only in the case of the spec being a request for an in-band decryption key from the HLS manifest.

However all I can see coming in the DataSpec is a uri, from which heuristically we can deduce its a key but this is hard to represent algorithmically as my key urls can be literally of any scheme.

When handling in-band keys for streaming I can create an HlsDataSource on my MediaSource.Factory:

   val hlsMediaSourceFactory: MediaSource.Factory =
        HlsMediaSource.Factory(hlsDataSourceFactory),

and HlsDataSourceFactory allows me to provide different DataSources depending on type:

    override fun createDataSource(dataType: Int): DataSource {
        return if (dataType == C.DATA_TYPE_DRM) {
            KeyDataSource()
        } else {
            defaultHlsDataSourceFactory.createDataSource(dataType)
        }
    }

However for downloads the HlsDownloader implementation makes no distinction between Segments and keys, everything is returned as a Segment to be fetched:

 if (seenEncryptionKeyUris.add(keyUri)) {
        out.add(new Segment(startTimeUs, SegmentDownloader.getCompressibleDataSpec(keyUri)));
      }

(the only differnece being the ALLOW_GZIP flag). I guess it would be convenient if a datatype indication would be given in the DataSpec as customData

Is there any way Im missing to employ a different dataSource for the key retrieval?