writeAll method
Iterates over the given objects and writes them in sequence.
If separator is provided, a write with the separator is performed
between any two elements of objects.
This operation is non-blocking. See flush or done for how to get any errors generated by this call.
Implementation
@override
void writeAll(Iterable<dynamic> objects, [String separator = ""]) {
  _inner.writeAll(objects);
  if (headers.contentType != ContentType.binary) {
    try {
      _sendBuffer?.writeAll(objects, separator);
    } catch (ex) {
      // log error if required
    }
    _checkAndResetBufferIfRequired();
  }
}