Asynchronously writes the contents of @provider to @stream in the given
@mime_type.
When the operation is finished @callback will be called. You must then call
[method@Gdk.ContentProvider.write_mime_type_finish] to get the result
of the operation.
The given mime type does not need to be listed in the formats returned by
[method@Gdk.ContentProvider.ref_formats]. However, if the given GType is
not supported, #G_IO_ERROR_NOT_SUPPORTED will be reported.
Asynchronously writes the contents of @provider to @stream in the given @mime_type.
When the operation is finished @callback will be called. You must then call [method@Gdk.ContentProvider.write_mime_type_finish] to get the result of the operation.
The given mime type does not need to be listed in the formats returned by [method@Gdk.ContentProvider.ref_formats]. However, if the given GType is not supported, #G_IO_ERROR_NOT_SUPPORTED will be reported.
The given @stream will not be closed.