Hi Team! I'm attempting to create a backend service for a load balancer using Pulumi, including a health check and mapping an instance group to the backend service. However, I'm encountering an issue where the resource creation is failing. Here’s the code I'm using:

python
backend_service = gcp.compute.BackendService(
    "backend_service",
    name="new_backend_service",
    backends=[gcp.compute.BackendServiceBackendArgs(
        group=["projects/{project}/zones/{zone}/instanceGroups/{instance_group}"],
    )],
    health_checks=["projects/{project}/global/healthChecks/{health_check}"],
    load_balancing_scheme="EXTERNAL",
    port_name="test",
    timeout_sec=30,
    protocol="HTTP",
    connection_draining_timeout_sec=300,
    log_config=gcp.compute.BackendServiceLogConfigArgs(
        enable=True,
        sample_rate=1,
    ),
    locality_lb_policies=[gcp.compute.BackendServiceLocalityLbPolicyPolicyArgs(
        name="ROUND_ROBIN",
    )]
)

However, I’m getting the following error:

raise AssertionError(f"Unexpected type. Expected 'list' got '{typ}'")
AssertionError: Unexpected type. Expected 'list' got '<class 'str'>'

Could you help me identify what’s causing this issue?