protected static String buildRequestBody(String query, String operationName, JsonObject variables) {
        JsonObject jsonObject = new JsonObject();
        jsonObject.put("query", query);
        jsonObject.put("operationName", operationName);
        jsonObject.put("variables", variables != null ? variables : new JsonObject());
        return jsonObject.toJson();
    }
@Test
    public void shouldBuildRequestBodyWithQuery() {
        String query = "queryText";

        String body = GraphqlProducer.buildRequestBody(query, null, null);

        String expectedBody = "{"
                              + "\"query\":\"queryText\","
                              + "\"operationName\":null,"
                              + "\"variables\":{}"
                              + "}";
        assertEquals(expectedBody, body);
    }