Feat/stackittpr 20 region adjustments | tfp (migrate first service to new regions concept) (#664)

* feat: completed bucket and credential group

* feat: fix linter warnings

* feat: updated documentation

* feat: updated to current version of the regional api

* feat: implement review findings

* feat: implement further review findings

* fix: make sure region is stored for the data-source in the state

stackit/internal/utils/regions.go

@@ -0,0 +1,39 @@
+package utils
+
+import (
+	"context"
+
+	"github.com/hashicorp/terraform-plugin-framework/path"
+	"github.com/hashicorp/terraform-plugin-framework/resource"
+	"github.com/hashicorp/terraform-plugin-framework/types"
+	"github.com/stackitcloud/terraform-provider-stackit/stackit/internal/core"
+)
+
+// AdaptRegion rewrites the region of a terraform plan
+func AdaptRegion(ctx context.Context, configRegion types.String, planRegion *types.String, defaultRegion string, resp *resource.ModifyPlanResponse) {
+	// Get the intended region. This is either set directly set in the individual
+	// config or the provider region has to be used
+	var intendedRegion types.String
+	if configRegion.IsNull() {
+		if defaultRegion == "" {
+			core.LogAndAddError(ctx, &resp.Diagnostics, "set region", "no region defined in config or provider")
+			return
+		}
+		intendedRegion = types.StringValue(defaultRegion)
+	} else {
+		intendedRegion = configRegion
+	}
+
+	// check if the currently configured region corresponds to the planned region
+	// on mismatch override the planned region with the intended region
+	// and force a replace of the resource
+	p := path.Root("region")
+	if !intendedRegion.Equal(*planRegion) {
+		resp.RequiresReplace.Append(p)
+		*planRegion = intendedRegion
+	}
+	resp.Diagnostics.Append(resp.Plan.SetAttribute(ctx, p, *planRegion)...)
+	if resp.Diagnostics.HasError() {
+		return
+	}
+}