Fix breaking change

Signed-off-by: Archer <naarcha@amazon.com>

spec/schemas/cluster.reroute.yaml

@@ -121,34 +121,26 @@ components:
         - node
         - shard
     Metric:
-      oneOf:
-        - type: string
-          const: _all
-          description: Returns all available metrics.
-        - type: string
-          const: blocks
-          description: Returns information about cluster-level blocks.
-        - type: string
-          const: cluster_manager_node
-          description: Returns information about the current cluster manager node.
-        - type: string
-          const: master_node
-          description: The alias for `cluster_manager_node`. Deprecated, but maintained for backwards compatibility.
-        - type: string
-          const: metadata
-          description: Returns the cluster state metadata.
-        - type: string
-          const: nodes
-          description: Returns information about nodes in the cluster.
-        - type: string
-          const: routing_nodes
-          description: Returns the node-level shard allocations.
-        - type: string
-          const: routing_table
-          description: Returns index-level shard allocations.
-        - type: string
-          const: version
-          description: Returns the cluster state version.
+      type: string
+      enum:
+        - _all
+        - blocks
+        - cluster_manager_node
+        - master_node
+        - metadata
+        - nodes
+        - routing_nodes
+        - routing_table
+        - version
+      enumDescriptions:
+        _all: Returns all available metrics.
+        blocks: Returns information about cluster level blocks.
+        cluster_manager_node: Returns information about the current cluster manager node.
+        master_node: An alias for `cluster_manager_node`. Deprecated, but maintained for backwards compatibility.
+        metadata: Returns the cluster state metadata
+        nodes: Returns information about nodes in the cluster.
+        routing_nodes: Returns the node-level shard allocations.
+        version: Returns the cluster state version.
     RerouteExplanation:
       type: object
       properties: