Import FoundationEssentials instead of Foundation when available (#159)

Author: Cyberbeni

Sources/MQTTNIO/AsyncAwaitSupport/MQTTClient+async.swift

@@ -11,7 +11,12 @@
 //
 //===----------------------------------------------------------------------===//
 
+#if canImport(FoundationEssentials)
+import Dispatch
+import FoundationEssentials
+#else
 import Foundation
+#endif
 import NIOCore
 
 @available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)

Sources/MQTTNIO/AsyncAwaitSupport/MQTTClientV5+async.swift

@@ -11,7 +11,11 @@
 //
 //===----------------------------------------------------------------------===//
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
 import Foundation
+#endif
 import NIOCore
 
 @available(macOS 12.0, iOS 15.0, watchOS 8.0, tvOS 15.0, *)

Sources/MQTTNIO/MQTTConnection.swift

@@ -11,7 +11,11 @@
 //
 //===----------------------------------------------------------------------===//
 
+#if canImport(FoundationEssentials)
+import FoundationEssentials
+#else
 import Foundation
+#endif
 #if canImport(Network)
 import Network
 #endif

Sources/MQTTNIO/MQTTPacket.swift

@@ -623,7 +623,7 @@ struct MQTTAuthPacket: MQTTPacket {
 
 /// MQTT incoming packet parameters.
 struct MQTTIncomingPacket: MQTTPacket {
-    var description: String { "Incoming Packet 0x\(String(format: "%x", self.type.rawValue))" }
+    var description: String { "Incoming Packet 0x\(String(self.type.rawValue, radix: 16))" }
 
     /// Type of incoming MQTT packet.
     let type: MQTTPacketType