All request handlers should be able to read `BytesTransportRequest` to
a class than can copied by re-serializing. Direct copying was only
necessary by the legacy `JOIN_VALIDATE_ACTION_NAME` request handler.

See elastic#89926

All request handlers should be able to read `BytesTransportRequest` to
a class than can copied by re-serializing. Direct copying was only
necessary by the legacy `JOIN_VALIDATE_ACTION_NAME` request handler.

See elastic#89926

All request handlers should be able to read `BytesTransportRequest` to
a class than can copied by re-serializing. Direct copying was only
necessary by the legacy `JOIN_VALIDATE_ACTION_NAME` request handler.

See elastic#89926

…)"

This reverts commit 530d150.

Since 8.3.0 (elastic#85380) we have sent join-validation requests as a
`BytesTransportRequest` to facilitate sharing these large messages (and
the work needed to create them) amongst all nodes that join the cluster
at around the same time. For BwC with versions earlier than 8.3.0 we use
a `ValidateJoinRequest` class to represent the received data, whichever
scheme it uses. We no longer need to maintain this compatibility, so we
can use a bare `BytesTransportRequest` on both sender and receiver, and
therefore drop the `ValidateJoinRequest` adapter and the special-cased
assertion in `MockTransportService`.

Relates elastic#114808 which was reverted in elastic#117200.

Reverts #114808 and unmutes #117024 which was a related failure.

Since 8.3.0 (elastic#85380) we have sent join-validation requests as a
`BytesTransportRequest` to facilitate sharing these large messages (and
the work needed to create them) amongst all nodes that join the cluster
at around the same time. For BwC with versions earlier than 8.3.0 we use
a `ValidateJoinRequest` class to represent the received data, whichever
scheme it uses. We no longer need to maintain this compatibility, so we
can use a bare `BytesTransportRequest` on both sender and receiver, and
therefore drop the `ValidateJoinRequest` adapter and the special-cased
assertion in `MockTransportService`.

Relates elastic#114808 which was reverted in elastic#117200.

Since 8.3.0 (#85380) we have sent join-validation requests as a
`BytesTransportRequest` to facilitate sharing these large messages (and
the work needed to create them) amongst all nodes that join the cluster
at around the same time. For BwC with versions earlier than 8.3.0 we use
a `ValidateJoinRequest` class to represent the received data, whichever
scheme it uses. We no longer need to maintain this compatibility, so we
can use a bare `BytesTransportRequest` on both sender and receiver, and
therefore drop the `ValidateJoinRequest` adapter and the special-cased
assertion in `MockTransportService`.

Relates #114808 which was reverted in #117200.

Reverts elastic#114808 and unmutes elastic#117024 which was a related failure.

Since 8.3.0 (elastic#85380) we have sent join-validation requests as a
`BytesTransportRequest` to facilitate sharing these large messages (and
the work needed to create them) amongst all nodes that join the cluster
at around the same time. For BwC with versions earlier than 8.3.0 we use
a `ValidateJoinRequest` class to represent the received data, whichever
scheme it uses. We no longer need to maintain this compatibility, so we
can use a bare `BytesTransportRequest` on both sender and receiver, and
therefore drop the `ValidateJoinRequest` adapter and the special-cased
assertion in `MockTransportService`.

Relates elastic#114808 which was reverted in elastic#117200.