[api] add the special "" option for refresh

scripts/generate/overrides.js

@@ -210,5 +210,35 @@ function (spec) {
         '/_delete_by_query/{task_id}/_rethrottle'
       ]
     }
+  },
+  {
+    version: '>=5.0.0',
+    mergeConcatParams: {
+      bulk: {
+        refresh: {
+          options: ['']
+        }
+      },
+      create: {
+        refresh: {
+          options: ['']
+        }
+      },
+      index: {
+        refresh: {
+          options: ['']
+        }
+      },
+      update: {
+        refresh: {
+          options: ['']
+        }
+      },
+      delete: {
+        refresh: {
+          options: ['']
+        }
+      }
+    }
   }
 ];

src/lib/apis/master.js

@@ -41,7 +41,8 @@ api.bulk = ca({
       options: [
         'true',
         'false',
-        'wait_for'
+        'wait_for',
+        ''
       ]
     },
     routing: {
@@ -1636,7 +1637,8 @@ api['delete'] = ca({
       options: [
         'true',
         'false',
-        'wait_for'
+        'wait_for',
+        ''
       ]
     },
     routing: {
@@ -2408,7 +2410,8 @@ api.index = ca({
       options: [
         'true',
         'false',
-        'wait_for'
+        'wait_for',
+        ''
       ]
     },
     routing: {
@@ -6627,7 +6630,8 @@ api.update = ca({
       options: [
         'true',
         'false',
-        'wait_for'
+        'wait_for',
+        ''
       ]
     },
     retryOnConflict: {