 ///
 /// This upgrader assumes that the `HTTPServerUpgradeHandler` will appropriately mutate the pipeline to
 /// remove the HTTP `ChannelHandler`s.
-public final class NIOWebSocketServerUpgrader: HTTPServerProtocolUpgrader {
+public final class NIOWebSocketServerUpgrader: HTTPServerProtocolUpgrader, @unchecked Sendable {
+    // This type *is* Sendable but we can't express that properly until Swift 5.7. In the meantime
+    // the conformance is `@unchecked`.
+
     /// RFC 6455 specs this as the required entry in the Upgrade header.
     public let supportedProtocol: String = "websocket"
 

        }
    }
}

#if swift(>=5.6)
@available(*, unavailable)
extension NIOWebSocketServerUpgrader: Sendable {}
#endif


    private let automaticErrorHandling: Bool

    #if swift(>=5.7)
    // FIXME: remove @unchecked when 5.7 is the minimum supported version.
    /// Create a new `NIOWebSocketServerUpgrader`.
    ///
    /// - parameters:
