Firewall rule attributes cannot be removed / perpetual change plan

[kbcz1989]

Describe the bug
Removing attribute(setting it to null or empty string) from firewall rule definition does not remove the attribute and next terraform plan wants to make same changes.

To Reproduce
Steps to reproduce the behavior:

1. Create a resource proxmox_virtual_environment_firewall_rules
2. Run terraform apply
3. Remove one of the attributes from defined rule
4. Run terraform apply - it "successfully" removes the rule
5. Next terraform plan wants to remove it again

Please also provide a minimal Terraform configuration that reproduces the issue.

Before the change:

resource "proxmox_virtual_environment_firewall_rules" "inbound" {
  node_name = var.node_name
  vm_id     = var.vm_id

  rule {
    type    = "in"
    action  = "ACCEPT"
    comment = "Allow HTTP"
    dest    = "192.168.1.5"
    dport   = "80"
    proto   = "tcp"
    log     = "info"
  }

  rule {
    type   = "in"
    action = "ACCEPT"
    comment = "Allow HTTPS"
    dest = "192.168.1.5"
    dport   = "443"
    proto   = "tcp"
    log = "info"
  }
}

After the change:

resource "proxmox_virtual_environment_firewall_rules" "inbound" {
  node_name = var.node_name
  vm_id     = var.vm_id

  rule {
    type    = "in"
    action  = "ACCEPT"
    comment = "Allow HTTP"
    dest    = "192.168.1.5"
    dport   = "80"
    proto   = "tcp"
    log     = "info"
  }

  rule {
    type   = "in"
    action = "ACCEPT"
    #comment = "Allow HTTPS"
    dest = "192.168.1.5"
    #dport   = "443"
    #proto   = "tcp"
    log = "info"
  }
}

Expected behavior
Attributes removed from config should be removed from resource.

Screenshots

Additional context
I am suspecting this is due to provider not sending null parameters at all. Comparing GUI and provider actions suggests the same:
Provider:
tf_http_req_body="action=ACCEPT&comment=Allow+HTTP&dest=192.168.1.5&dport=80&enable=1&log=info&pos=0&proto=tcp&type=in"

GUI:
type=in&action=ACCEPT&delete=iface&source=&dest=192.168.1.5&enable=1&macro=&proto=&sport=&dport=&comment=&log=info&icmp-type=&digest=0929e8b4b3604b3b14a620d53a5aa86f13c838e4

• Single or clustered Proxmox: clustered
• Proxmox version: 8.2.4
• Provider version (ideally it should be the latest version): 0.62.0
• Terraform/OpenTofu version: terraform 1.8.3
• OS (where you run Terraform/OpenTofu from): Ubuntu 22.04
• Debug logs (TF_LOG=DEBUG terraform apply):
  https://gist.github.com/kbcz1989/78344a82c7a4ee29024b01033673c8df

[kbcz1989]

Possibly related to "omitempty" here:

terraform-provider-proxmox/proxmox/firewall/rules.go

Lines 32 to 45 in 35cbe98

	type BaseRule struct {
	Comment *string `json:"comment,omitempty" url:"comment,omitempty"`
	Dest *string `json:"dest,omitempty" url:"dest,omitempty"`
	Digest *string `json:"digest,omitempty" url:"digest,omitempty"`
	DPort *string `json:"dport,omitempty" url:"dport,omitempty"`
	Enable *types.CustomBool `json:"enable,omitempty" url:"enable,omitempty,int"`
	ICMPType *string `json:"icmp-type,omitempty" url:"icmp-type,omitempty"`
	IFace *string `json:"iface,omitempty" url:"iface,omitempty"`
	Log *string `json:"log,omitempty" url:"log,omitempty"`
	Macro *string `json:"macro,omitempty" url:"macro,omitempty"`
	Proto *string `json:"proto,omitempty" url:"proto,omitempty"`
	Source *string `json:"source,omitempty" url:"source,omitempty"`
	SPort *string `json:"sport,omitempty" url:"sport,omitempty"`
	}