ValidateQueryRequest always returns true

Elastic Stack Elasticsearch
1

Trying to write a simple unit test to validate our queries using version 1.5.2. When I run this in our test class, response.isValid() always comes back true:

ValidateQueryRequest request = new ValidateQueryRequest("test").source("foo");
ValidateQueryResponse response = client().admin().indices().validateQuery(request).actionGet();

Is this a known bug, or am I missing something required?