public String[] queryParamsValues(String queryParam) {
        return servletRequest.getParameterValues(queryParam);
    }
Gets all the values of the query param
Example: query parameter 'id' from the following request URI: /hello?id=foo&amp;id=bar

@param queryParam the query parameter
@return the values of the provided queryParam, null if it doesn't exists
src/main/java/spark/Request.java