[console] Replace text/plain fallback with application/json (#12294)

* [console] Always set content-type for requests to es

* [console] always set content type to application/json if there is a body

* remove extra space

src/core_plugins/console/public/src/es.js

@@ -7,6 +7,11 @@ export function getVersion() {
   return esVersion;
 }
 
+export function getContentType(body) {
+  if (!body) return;
+  return 'application/json';
+}
+
 export function send(method, path, data) {
   var wrappedDfd = $.Deferred();
 
@@ -15,29 +20,10 @@ export function send(method, path, data) {
     method = "POST";
   }
 
-  let contentType;
-  if (data) {
-    try {
-      JSON.parse(data);
-      contentType = 'application/json';
-    }
-    catch (e) {
-      try {
-        data.split('\n').forEach(line => {
-          if (!line) return;
-          JSON.parse(line);
-        });
-        contentType = 'application/x-ndjson';
-      } catch (e){
-        contentType = 'text/plain';
-      }
-    }
-  }
-
   var options = {
     url: '../api/console/proxy?' + formatQueryString({ path, method }),
     data,
-    contentType,
+    contentType: getContentType(data),
     cache: false,
     crossDomain: true,
     type: 'POST',

src/core_plugins/console/public/tests/src/content_type.js

@@ -0,0 +1,26 @@
+import { getContentType } from '../../src/es';
+
+const { test, module, equal } = window.QUnit;
+
+const APPLICATION_JSON = 'application/json';
+
+module('Content type');
+
+test('body', () => {
+  const contentType = getContentType([
+    JSON.stringify({
+      foo: 'baz'
+    }),
+    JSON.stringify({
+      foo: 'bar'
+    })
+  ].join('\n'))
+
+  equal(contentType, APPLICATION_JSON);
+});
+
+test('no body', () => {
+  const contentType = getContentType('');
+
+  equal(contentType, undefined);
+});

src/core_plugins/console/public/tests/tests.js

@@ -18,6 +18,7 @@ require('ui/chrome')
     QUnit.config.autostart = false;
     QUnit.init();
 
+    require('./src/content_type.js');
     require('./src/utils_tests.js');
     require('./src/url_autocomplete_tests.js');
     require('./src/url_params_tests.js');