You can add this section to log4j.properties file:
logger.rorignore.name = tech.beshu.ror.es.request.queries
logger.rorignore.level = error
logger.rorignore.additivity = false
We’ve recently improved our FLS engine (details here: https://github.com/beshu-tech/readonlyrest-docs/blob/master/fls_engine.md#fls-engine). For some kind of queries we can improve the performance of the request, but other have to be handled in old style. The log tells us that the fastest method cannot be used. In general user should not be interested in this message, because it tells about our internal implementation details. With one exception, when you as a user ,pick to use the fastest method only (it’s described in docs). So, we have to improve the logging, because it seems that the log level should be different depending on ROR settings 
But as I said, at the moment you can ignore it 