serialize OcaGroup members as object numbers, not full objects

The default @OcaDeviceProperty serialization for the members property
attempted to JSON-encode the full OcaRoot objects, which is both
incorrect and could cause serialization failures. Override serialize()
and deserialize() to encode members as [OcaONo] and resolve them back
on deserialization, matching the wire protocol representation.

Author: lhoward

Sources/SwiftOCADevice/OCC/ControlClasses/Agents/Group.swift

@@ -87,6 +87,66 @@ open class OcaGroup<Member: OcaRoot>: OcaAgent {
     try? await notifySubscribers(actionObjects: members, changeType: .itemDeleted)
   }
 
+  private static var _membersPropertyID: OcaPropertyID { OcaPropertyID("3.1") }
+
+  override open func serialize(
+    flags: OcaRoot.SerializationFlags = [],
+    isIncluded: OcaRoot.SerializationFilterFunction? = nil
+  ) throws -> [String: any Sendable] {
+    // exclude members from super.serialize() to avoid encoding full OcaRoot objects
+    let membersPropertyID = Self._membersPropertyID
+    let wrappedFilter: OcaRoot.SerializationFilterFunction = { object, propertyID, value in
+      if propertyID == membersPropertyID { return false }
+      return isIncluded?(object, propertyID, value) ?? true
+    }
+
+    var jsonObject = try super.serialize(flags: flags, isIncluded: wrappedFilter)
+
+    // encode members as object numbers
+    if isIncluded?(self, membersPropertyID, members) ?? true {
+      jsonObject[membersPropertyID.description] = members.map(\.objectNumber)
+    }
+
+    return jsonObject
+  }
+
+  override open func deserialize(
+    jsonObject: [String: Sendable],
+    flags: DeserializationFlags = []
+  ) async throws {
+    guard let deviceDelegate else { throw Ocp1Error.notConnected }
+
+    let membersKey = Self._membersPropertyID.description
+
+    // extract members before calling super to avoid needless deserialization
+    let memberONos = jsonObject[membersKey] as? [OcaONo]
+    var filteredJsonObject = jsonObject
+    filteredJsonObject.removeValue(forKey: membersKey)
+
+    try await super.deserialize(jsonObject: filteredJsonObject, flags: flags)
+
+    guard let memberONos else {
+      if flags.contains(.ignoreDecodingErrors) { return }
+      else { throw Ocp1Error.status(.badFormat) }
+    }
+
+    let resolvedMembers: [Member] = try await memberONos.asyncCompactMap { @Sendable memberONo in
+      guard let object = await deviceDelegate.objects[memberONo] else {
+        if flags.contains(.ignoreUnknownObjectNumbers) { return nil }
+        else { throw Ocp1Error.objectNotPresent(memberONo) }
+      }
+
+      guard let member = object as? Member else {
+        if flags.contains(.ignoreObjectClassMismatches) { return nil }
+        else { throw Ocp1Error.objectClassMismatch }
+      }
+
+      return member
+    }
+
+    try await set(members: resolvedMembers)
+  }
+
   override open func handleCommand(
     _ command: Ocp1Command,
     from controller: any OcaController