protected override Task WriteEndAttributeAsync()
{
if (IsClosed)
ThrowClosed();
if (_writeState != WriteState.Attribute)
throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new InvalidOperationException(SR.Format(SR.XmlInvalidWriteState, "WriteEndAttribute", WriteState.ToString())));
return WriteEndAttributeAsyncImpl();
}