feat: Introduce BeforeWrite hook - and override the implementation within ProductConfig to properly associate the first sandbox and deployments added.

Author: paulhazen

com.playeveryware.eos/Runtime/Core/Config/Config.cs

@@ -499,6 +499,8 @@ private async Task EnsureConfigFileExistsAsync()
         /// <returns>Task</returns>
         public virtual async Task WriteAsync(bool prettyPrint = true)
         {
+            BeforeWrite();
+
             // Set the schema version to the current before writing.
             schemaVersion = CURRENT_SCHEMA_VERSION;
 
@@ -521,6 +523,8 @@ public virtual async Task WriteAsync(bool prettyPrint = true)
         /// </param>
         public virtual void Write(bool prettyPrint = true)
         {
+            BeforeWrite();
+
             // Set the schema version to the current before writing.
             schemaVersion = CURRENT_SCHEMA_VERSION;
 
@@ -535,6 +539,12 @@ public virtual void Write(bool prettyPrint = true)
             OnWriteCompleted();
         }
 
+        protected virtual void BeforeWrite()
+        {
+            // Optionally override this function in a deriving class. Default
+            // behavior is to take no action.
+        }
+
         protected virtual void OnWriteCompleted()
         {
             // Optionally override for deriving classes. Default behavior is to 

com.playeveryware.eos/Runtime/Core/Config/ProductConfig.cs

@@ -152,6 +152,17 @@ protected override void OnReadCompleted()
         // editor.
 #if UNITY_EDITOR
 
+        protected override void BeforeWrite()
+        {
+            // If there is one deployment, and one sandbox, then make sure they
+            // are linked to each other.
+            // But only do this if they have been newly added
+            if (!_deploymentDefined && Environments.Deployments.Count ==1 && Environments.Sandboxes.Count == 1)
+            {
+                Environments.Deployments[0].Value.SandboxId = Environments.Sandboxes[0].Value;
+            }
+        }
+
         protected override void OnWriteCompleted()
         {
             // If when the config was last read there was a deployment defined,

com.playeveryware.eos/Runtime/Core/EOS_SDK_Additions/EOSClientCredentials.cs

@@ -83,6 +83,15 @@ public static bool IsEncryptionKeyValid(string encryptionKey)
                 !s_invalidEncryptionKeyRegex.Match(encryptionKey).Success;
         }
 
+        public bool IsComplete
+        {
+            get
+            {
+                // TODO: Provide more comprehensive data validation (see Epic documentation for requirements)
+                return !string.IsNullOrWhiteSpace(ClientId) && !string.IsNullOrWhiteSpace(ClientSecret);
+            }
+        }
+
         /// <summary>
         /// Determines whether the encryption key for the credentials is valid.
         /// </summary>