chore: Follow-up changes for PR 3140 (#3154)

* document isKnown

* simplify checkBlocks

* final period

Author: lantoli

internal/service/advancedcluster/resource_advanced_cluster_test.go

@@ -1387,11 +1387,11 @@ func TestAccMockableAdvancedCluster_removeBlocksFromConfig(t *testing.T) {
 		Steps: []resource.TestStep{
 			{
 				Config: configBlocks(t, projectID, clusterName, true),
-				Check:  checkBlocks(projectID, clusterName, true),
+				Check:  checkBlocks(true),
 			},
 			{
 				Config: configBlocks(t, projectID, clusterName, false),
-				Check:  checkBlocks(projectID, clusterName, false),
+				Check:  checkBlocks(false),
 			},
 			acc.TestStepImportCluster(resourceName),
 		},
@@ -1567,7 +1567,7 @@ func configBlocks(t *testing.T, projectID, clusterName string, firstStep bool) s
 	`, projectID, clusterName, instanceSize1, extraConfig0, extraConfig1))
 }
 
-func checkBlocks(projectID, clusterName string, firstStep bool) resource.TestCheckFunc {
+func checkBlocks(firstStep bool) resource.TestCheckFunc {
 	checksMap := map[string]string{
 		"replication_specs.0.region_configs.0.electable_specs.0.instance_size": "M10",
 		"replication_specs.0.region_configs.0.electable_specs.0.node_count":    "5",

internal/service/advancedclustertpf/plan_modifier.go

@@ -271,6 +271,7 @@ func copyAttrIfDestNotKnown[T attr.Value](src, dest *T) {
 	}
 }
 
+// isKnown returns true if the attribute is known (not null or unknown). Note that !isKnown is not the same as IsUnknown because null is !isKnown but not IsUnknown.
 func isKnown(attribute attr.Value) bool {
 	return !attribute.IsNull() && !attribute.IsUnknown()
 }