Revert "Add Validation for IAP domain and allowlist" (GoogleCloudPlat…

…form#557)

Revert "Add Validation for IAP domain and allowlist (GoogleCloudPlatform#542)"

This reverts commit dd7668e.

modules/iap/iap.tf

@@ -21,23 +21,6 @@ data "google_project" "project" {
   project_id = var.project_id
 }
 
-## Check if domain and members_allowlist is provided
-data "null_data_source" "domain_validation" {
-  inputs = {}
-
-  lifecycle {
-    precondition {
-      condition     = var.domain != ""
-      error_message = "IAP configuration requires domain name, Please provide a valid domain name for ${var.app_name} application."
-    }
-
-    precondition {
-      condition     = length(var.members_allowlist) != 0
-      error_message = "IAP configuration requires allowlisting users. Please provide a valid allowlist for ${var.app_name} application."
-    }
-  }
-}
-
 # Creates a "Brand", equivalent to the OAuth consent screen on Cloud console
 resource "google_iap_brand" "project_brand" {
   count             = var.create_brand ? 1 : 0