title: Terraform detects changes to availability domain on data lookup
body: <p>Terraform detects changes to availability_domain and forces a replacement when no change has taken place.</p>
  <p>When I run <code>terraform apply</code> a second time with no changes made, terraform forces a replacement of my instance, this is due to the <code>availability_domain</code> lookup, is this a bug, or is my lookup incorrect?</p>
  <pre><code>  # module.services.oci_core_volume must be replaced
  -/+ resource &quot;oci_core_volume&quot; &quot;disk_res_instance[&quot; {
        + auto_tuned_vpus_per_gb = (known after apply)
        ~ availability_domain    = &quot;REGION&quot; -&gt; (known after apply) # forces replacement
        + backup_policy_id       = (known after apply)
        ~ freeform_tags          = {} -&gt; (known after apply)
        ~ id                     = &quot;ocid1.volume.oc1.me-jeddah-1.abc&quot; -&gt; (known after apply)
        ~ is_auto_tune_enabled   = false -&gt; (known after apply)
        ~ is_hydrated            = true -&gt; (known after apply)
        + kms_key_id             = (known after apply)
        ~ size_in_mbs            = &quot;51200&quot; -&gt; (known after apply)
  </code></pre>
  <p>If I'm reading this correctly, it seems that the replacement is forced by the availability_domain, however, this remains unchanged.</p>
  <pre><code>resource &quot;oci_core_volume&quot; &quot;diskinstance&quot; {
    count               = 1
    availability_domain = data.oci_identity_availability_domains.ad_list.availability_domains[0][&quot;name&quot;]
  ...
  </code></pre>
  <p><strong>data</strong></p>
  <pre><code>data &quot;oci_identity_availability_domains&quot; &quot;ad_list&quot; {
    compartment_id = var.compartment_id
  }
  </code></pre>
  <p>Is it that each time the data look-up on the availability domains is being done it forces it to be replaced, or something else?</p>