bool isContentTypeCompressable(ContentType contentType)

Whether or not contentType has been configured to be compressed.

See also setAllowsCompression.

Source 

bool isContentTypeCompressable(ContentType contentType) {
  var subtypeCompress = _subtypeCompressionMap[contentType.primaryType];
  if (subtypeCompress != null) {
    if (subtypeCompress.containsKey(contentType.subType)) {
      return subtypeCompress[contentType.subType];
    }
  }

  return _primaryTypeCompressionMap[contentType.primaryType] ?? false;
}