Question on when a broker node is ready for answering SQL queries

We are running Druid 0.13.0-incubating, and would like some suggestions on how to check whether a broker node is ready for answering SQL queries.

As we understand it, when a broker node comes up, it issues SegmentMetadataQuery to refresh the metadata for datasources, and build the SQL table schema based on the refreshed metadata. Looks like it is possible for the broker to accept SQL queries before the metadata is refreshed. We believe that this is why some of our queries failed with “org.apache.calcite.sql.validate.SqlValidatorException: Object ‘testTable’ not found”.

My question is whether there is an endpoint we can check before issuing the SQL query to the broker nodes. If not, can we start the broker service only after the metadata is refreshed? I am new to Druid, but I am happy to contribute if this is the right way to go. Please let me know.