Add mapping method back referenced in other repos (#2636) (#2649)

Signed-off-by: Suraj Singh <surajrider@gmail.com>
Signed-off-by: Nicholas Walter Knize <nknize@apache.org>

(cherry picked from commit bcaa06b)

Co-authored-by: Suraj Singh <79435743+dreamer-89@users.noreply.github.com>

server/src/main/java/org/opensearch/action/admin/indices/create/CreateIndexRequest.java

@@ -245,14 +245,22 @@ public CreateIndexRequest mapping(String mapping) {
         return this;
     }
 
+    /**
+     * Adds mapping that will be added when the index gets created.
+     *
+     * @param source The mapping source
+     * @param xContentType The content type of the source
+     */
+    public CreateIndexRequest mapping(String source, XContentType xContentType) {
+        return mapping(new BytesArray(source), xContentType);
+    }
+
     /**
      * Adds mapping that will be added when the index gets created.
      *
      * @param source The mapping source
      * @param xContentType the content type of the mapping source
-     * @deprecated types are being removed
      */
-    @Deprecated
     private CreateIndexRequest mapping(BytesReference source, XContentType xContentType) {
         Objects.requireNonNull(xContentType);
         Map<String, Object> mappingAsMap = XContentHelper.convertToMap(source, false, xContentType).v2();