[Bug] elasticstack_kibana_security_detection_rule validation fails when index comes from for_each

[girtsLv]

Describe the bug
The elasticstack_kibana_security_detection_rule resource's schema validation incorrectly reports that index (or data_view_id) is not set when the index value comes from a for_each loop.

The error:

Error: Invalid Configuration

  with elasticstack_kibana_security_detection_rule.rules_eck,
  on rules_eck.tf line 1, in resource "elasticstack_kibana_security_detection_rule" "rules_eck":
   1: resource "elasticstack_kibana_security_detection_rule" "rules_eck" {

One of 'index' or 'data_view_id' must be set.

To Reproduce

1. Create a YAML file with rule definition including index:

name: Example rule
rule_id: example-rule
type: query
index:
  - logs-*
query: event.code: 1116

2. Create Terraform configuration that reads YAML files and creates resources:

locals {
  rules_dir   = "./rules_eck"
  rules_files = fileset(local.rules_dir, "*.yml")
  rules = {
    for f in local.rules_files :
    f => yamldecode(file("${local.rules_dir}/${f}"))
  }
}

resource "elasticstack_kibana_security_detection_rule" "rules_eck" {
  for_each = local.rules

  name        = each.value.name
  description = each.value.description
  type        = each.value.type
  rule_id     = each.value.rule_id
  index       = each.value.index
  
  # this works
  # index       = ["logs-*"]
}

3. Run terraform validate

Expected behavior
Validation should pass.
Verification shows the value exists: terraform console confirms local.rules["test_rule_eck.yml"].index contains the expected list

Debug output
n/a

Screenshots
n/a

Versions (please complete the following information):

• Provider: elasticstack (elastic/elasticstack)
• Provider Version: 0.12.2
• OS: Linux (WSL2)

Additional context
n/a