Update rest-api-spec (#4936)

Co-authored-by: pquentin <42327+pquentin@users.noreply.github.com>

Author: github-actions[bot]

output/schema/validation-errors.json

@@ -1,5 +1,14 @@
 {
   "endpointErrors": {
+    "cluster.allocation_explain": {
+      "request": [
+        "Request: missing json spec query parameter 'index'",
+        "Request: missing json spec query parameter 'shard'",
+        "Request: missing json spec query parameter 'primary'",
+        "Request: missing json spec query parameter 'current_node'"
+      ],
+      "response": []
+    },
     "msearch": {
       "request": [
         "Request: query parameter 'allow_no_indices' does not exist in the json spec",
@@ -11,12 +20,6 @@
       ],
       "response": []
     },
-    "reindex": {
-      "request": [
-        "Request: query parameter 'require_alias' does not exist in the json spec"
-      ],
-      "response": []
-    },
     "searchable_snapshots.clear_cache": {
       "request": [
         "Request: missing json spec query parameter 'index'"

specification/_json_spec/cluster.allocation_explain.json

@@ -19,6 +19,22 @@
       ]
     },
     "params": {
+      "index": {
+        "type": "string",
+        "description": "Specifies the name of the index that you would like an explanation for"
+      },
+      "shard": {
+        "type": "number",
+        "description": "Specifies the ID of the shard that you would like an explanation for"
+      },
+      "primary": {
+        "type": "boolean",
+        "description": "If true, returns explanation for the primary shard for the given shard ID"
+      },
+      "current_node": {
+        "type": "string",
+        "description": "Specifies the node ID or the name of the node to only explain a shard that is currently located on the specified node"
+      },
       "master_timeout": {
         "type": "time",
         "description": "Timeout for connection to master node"

specification/_json_spec/reindex.json

@@ -55,6 +55,11 @@
       "max_docs": {
         "type": "number",
         "description": "Maximum number of documents to process (default: all documents)"
+      },
+      "require_alias": {
+        "type": "boolean",
+        "default": false,
+        "description": "When true, requires destination to be an alias."
       }
     },
     "body": {