# Renamed replaced with superseded

Signed-off-by: Theo Truong <theotr@amazon.com>

DEVELOPER_GUIDE.md

@@ -84,6 +84,19 @@ This repository includes several penAPI Specification Extensions to fill in any
 - `x-global`: Denotes that the parameter is a global parameter that is included in every operation. These parameters are listed in the [root file](spec/opensearch-openapi.yaml).
 - `x-default`: Contains the default value of a parameter. This is often used to override the default value specified in the schema, or to avoid accidentally changing the default value when updating a shared schema.
 
+## Auto-generating Superseded Operations
+
+When an operation is superseded by another operation with **IDENTICAL FUNCTIONALITY**, that is a rename or a change in the URL, it should be listed in [_superseded_operations.yaml](./spec/_superseded_operations.yaml) file. The merger tool will automatically generate the superseded operation in the OpenAPI spec. The superseded operation will have `deprecated` and `x-ignorable` properties set to `true` to indicate that it should be ignored by the client generator.
+For example, if the `_superseded_operations.yaml` file contains the following entry:
+```yaml
+/_opendistro/_anomaly_detection/{nodeId}/stats/{stat}:
+  superseded_by: /_plugins/_anomaly_detection/{nodeId}/stats/{stat}
+  operations:
+    - GET
+    - POST
+```
+Then, the merger tool will generate 2 operations: `GET /_opendistro/_anomaly_detection/{nodeId}/stats/{stat}` and `POST /_opendistro/_anomaly_detection/{nodeId}/stats/{stat}` from `GET /_plugins/_anomaly_detection/{nodeId}/stats/{stat}` and `POST /_plugins/_anomaly_detection/{nodeId}/stats/{stat}` respectively, if they exist (A warning will be printed on the console if they do not). Note that the path parameter names do not need to match. So, if the actual superseding operations have path of `/_plugins/_anomaly_detection/{node_id}/stats/{stat_id}`, the merger tool will recognize that it is the same as `/_plugins/_anomaly_detection/{nodeId}/stats/{stat}` and generate the superseded operations accordingly with the correct path parameter names.
+
 ## Linting
 We have a linter that validates every `yaml` file in the `./spec` folder to assure that they follow the guidelines we have set. Check out the [Linter](tools/README.md#linter) tool for more information on how to run it locally. Make sure to run the linter before submitting a PR.