Fix databricks_workspace_binding for existing resources using external-location or storage-credential (#4611)

## Changes
Previously, the UC workspace binding API allowed users to specify
`external-location` and `storage-credential` for the securable type in
the [update securable workspace bindings
API](https://docs.databricks.com/api/workspace/workspacebindings/updatebindings).
This was changed to `external_location` and `storage_credential`.
However, for users who created these bindings using the older names,
those names were persisted in the `id` of the resource. As a result, the
securable type is always updated to the older name, causing a permanent
drift to appear.

This PR changes the `Read()` method of `databricks_workspace_binding` to
rewrite old-style securable types in this API to their new style names.
The result is that there is no longer a difference in the
`securable_type` attribute, which is the expected behavior.

## Tests
Added a unit test to verify that an ID in the old style would be
interpreted appropriately by the updated read method, resulting in no
diff when the ID contains `external-location` and the `securable_type`
is set to `external_location`.

---------

Co-authored-by: Alex Ott <[email protected]>

Author: mgyucht

NEXT_CHANGELOG.md

@@ -10,6 +10,7 @@
 
 ### Bug Fixes
 
+ * Fix `databricks_workspace_binding` for existing resources using `external-location` or `storage-credential` securable types ([#4611](https://github.com/databricks/terraform-provider-databricks/pull/4611)).
  * Suppress diff in `databricks_mlflow_experiment` name ([#4606](https://github.com/databricks/terraform-provider-databricks/pull/4606))
 
 ### Documentation

catalog/resource_workspace_binding.go

@@ -91,7 +91,9 @@ func ResourceWorkspaceBinding() common.Resource {
 				return fmt.Errorf("incorrect binding id: %s. Correct format: <workspace_id>|<securable_type>|<securable_name>", d.Id())
 			}
 			securableName := parts[2]
-			securableType := catalog.GetBindingsSecurableType(parts[1])
+			// Previously, users could specify "external-location" and "storage-credential" as the securable type.
+			// We need to convert them to "external_location" and "storage_credential" respectively.
+			securableType := catalog.GetBindingsSecurableType(strings.Replace(parts[1], "-", "_", -1))
 			workspaceId, err := strconv.ParseInt(parts[0], 10, 0)
 			if err != nil {
 				return fmt.Errorf("can't parse workspace_id: %w", err)

catalog/resource_workspace_binding_test.go

@@ -243,6 +243,32 @@ func TestSecurableWorkspaceBindings_Delete(t *testing.T) {
 	}.ApplyNoError(t)
 }
 
+func TestWorkspaceBindingsRead_OldStyleSecurableType(t *testing.T) {
+	qa.ResourceFixture{
+		Fixtures: []qa.HTTPFixture{
+			{
+				Method:   "GET",
+				Resource: "/api/2.1/unity-catalog/bindings/external_location/my_catalog?",
+				Response: catalog.WorkspaceBindingsResponse{
+					Bindings: []catalog.WorkspaceBinding{
+						{
+							BindingType: catalog.WorkspaceBindingBindingTypeBindingTypeReadOnly,
+							WorkspaceId: int64(1234567890101112),
+						},
+					},
+				},
+			},
+		},
+		Resource: ResourceWorkspaceBinding(),
+		ID:       "1234567890101112|external-location|my_catalog",
+		Read:     true,
+	}.ApplyAndExpectData(t, map[string]any{
+		"workspace_id":   1234567890101112,
+		"securable_type": "external_location",
+		"securable_name": "my_catalog",
+	})
+}
+
 func TestWorkspaceBindingsReadImport(t *testing.T) {
 	qa.ResourceFixture{
 		Fixtures: []qa.HTTPFixture{