无法访问原始类型值（字符串）的属性

我尝试通过我的 azure 函数将我的 apim 公共 ip 列入白名单：

apim.tf

data "azurerm_api_management" "main" {
  name                = "my-apim"
  resource_group_name = "my-rg"
}

output "apim_ip" {
  value = data.azurerm_api_management.main.public_ip_addresses
}

地形输出

apim_ip = tolist([
  "1.2.3.4",
])

func.tf

resource "azurerm_linux_function_app" "az_func" {
  name                = var.my_func_name
  resource_group_name = azurerm_resource_group.main.name
  location            = var.location

  storage_account_name       = azurerm_storage_account.main.name
  storage_account_access_key = azurerm_storage_account.main.primary_access_key

  service_plan_id = azurerm_service_plan.azfunc.id

  site_config {
    dynamic "ip_restriction" {
      for_each = data.azurerm_api_management.main.public_ip_addresses
      content {
        ip_address = data.azurerm_api_management.main.public_ip_address_id.value
      }
    }
  }
}

在terraform apply我不断收到错误消息：

无法访问原始类型值（字符串）的属性。

我究竟做错了什么？