kms key var must be a string

Author: chtakahashi

README.md

@@ -59,7 +59,7 @@ module "bootstrap" {
 | dynamodb\_table\_name | Name of the DynamoDB Table for locking Terraform state. | `string` | `"terraform-state-lock"` | no |
 | dynamodb\_table\_tags | Tags of the DynamoDB Table for locking Terraform state. | `map(string)` | ```{ "Automation": "Terraform", "Name": "terraform-state-lock" }``` | no |
 | enable\_s3\_public\_access\_block | Bool for toggling whether the s3 public access block resource should be enabled. | `bool` | `true` | no |
-| kms\_master\_key\_id | The AWS KMS master key ID used for the SSE-KMS encryption of the state bucket. | `string` | `null` | no |
+| kms\_master\_key\_id | The AWS KMS master key ID used for the SSE-KMS encryption of the state bucket. | `string` | `""` | no |
 | log\_bucket\_tags | Tags to associate with the bucket storing the Terraform state bucket logs | `map(string)` | ```{ "Automation": "Terraform" }``` | no |
 | log\_bucket\_versioning | A string that indicates the versioning status for the log bucket. | `string` | `"Disabled"` | no |
 | log\_name | Log name (for backwards compatibility this can be modified to logs) | `string` | `"log"` | no |

variables.tf

@@ -83,7 +83,7 @@ variable "manage_account_alias" {
 
 variable "kms_master_key_id" {
   type        = string
-  default     = null
+  default     = ""
   description = "The AWS KMS master key ID used for the SSE-KMS encryption of the state bucket."
 }