Remove special-case when no fields are found

Author: romseygeek

rest-api-spec/src/main/resources/rest-api-spec/test/indices.get_field_mapping/20_missing_field.yml

@@ -16,4 +16,4 @@
         index: test_index
         fields: not_existent
 
-  - match: { '': {}}
+  - match: { 'test_index.mappings': {}}

server/src/main/java/org/elasticsearch/rest/action/admin/indices/RestGetFieldMappingAction.java

@@ -67,12 +67,7 @@ public RestChannelConsumer prepareRequest(final RestRequest request, final NodeC
                     @Override
                     public RestResponse buildResponse(GetFieldMappingsResponse response, XContentBuilder builder) throws Exception {
                         Map<String, Map<String, FieldMappingMetaData>> mappingsByIndex = response.mappings();
-
-                        boolean isPossibleSingleFieldRequest = indices.length == 1 && fields.length == 1;
-                        if (isPossibleSingleFieldRequest && isFieldMappingMissingField(mappingsByIndex)) {
-                            return new BytesRestResponse(OK, builder.startObject().endObject());
-                        }
-
+                        
                         RestStatus status = OK;
                         if (mappingsByIndex.isEmpty() && fields.length > 0) {
                             status = NOT_FOUND;