Can't build AWS SDK on MacOS using CLion

There is an error building the Swift NIO library:

Toolchain I have installed /Library/Developer/Toolchains/swift-5.2.5-RELEASE.xctoolchain

Error 

/Users/andrew/develop/demos/dynaswift/.build/checkouts/swift-nio-transport-services/Sources/NIOTransportServices/NIOTSChannelOptions.swift:114:67: error: 'EstablishmentReport' is not a member type of 'NWConnection'
public typealias Value = EventLoopFuture<NWConnection.EstablishmentReport?>
~~~~~~~~~~~~ ^
Network.NWConnection:2:20: note: 'NWConnection' declared here
final public class NWConnection : CustomDebugStringConvertible {
^

I believe that EstablishmentReport is a member of NWConnection. See https://developer.apple.com/documentation/network/nwconnection/establishmentreport