Clear file cache was added in OpenSearch 2.8.0.

Signed-off-by: dblock <[email protected]>

spec/namespaces/indices.yaml

@@ -2766,6 +2766,7 @@ components:
         $ref: '../schemas/_common.yaml#/components/schemas/Fields'
       style: form
     indices.clear_cache::query.file:
+      x-version-added: '2.8'
       in: query
       name: file
       description: If true, clears the unused entries from the file cache on nodes with the Search role.

tests/indices/cache.yaml

@@ -22,7 +22,6 @@ chapters:
       expand_wildcards: none
       fielddata: true
       fields: '*'
-      file: false
       index:
         - movies
       ignore_unavailable: true
@@ -32,6 +31,16 @@ chapters:
       status: 200
       payload:
         _shards: {}
+  - synopsis: Clear all cache, file=true (POST).
+    version: '>= 2.8.0'
+    path: /_cache/clear
+    method: POST
+    parameters:
+      file: true
+    response:
+      status: 200
+      payload:
+        _shards: {}
   - synopsis: Clear index cache (POST).
     path: /{index}/_cache/clear
     method: POST