Adding the merge_type param to the ingest simulate API

Author: masseyke

output/schema/schema.json

@@ -1,5 +1,12 @@
 {
-  "endpointErrors": {},
+  "endpointErrors": {
+    "simulate.ingest": {
+      "request": [
+        "Request: query parameter 'merge_type' does not exist in the json spec"
+      ],
+      "response": []
+    }
+  },
   "generalErrors": [
     "Dangling type '_global.scripts_painless_execute:PainlessExecutionPosition'",
     "Dangling type '_global.scripts_painless_execute:PainlessScript'",

output/schema/validation-errors.json

@@ -75,6 +75,13 @@ export interface Request extends RequestBase {
      * This value can be used to override the default pipeline of the index.
      */
     pipeline?: PipelineName
+    /**
+     * The way that mapping_additions ought to be merged into existing mappings -- in the way mapping changes are merged into an existing index, or in
+     * the way mapping changes are merged into existing templates. Some changes are allowed to templates that are not allowed to indices. For example,
+     * a field cannot be changed to an incompatible type in an index, but can in a template.
+     * @server_default index
+     */
+    merge_type?: MergeType
   }
   body: {
     /**
@@ -98,3 +105,8 @@ export interface Request extends RequestBase {
     pipeline_substitutions?: Dictionary<string, Pipeline>
   }
 }
+
+enum MergeType {
+  index,
+  template
+}