public void log(LogTag tag) {
    try {
      REPL_LOG.info("REPL::{}: {}", tag.name(), mapper.writeValueAsString(this));
    } catch (Exception exception) {
      REPL_LOG.error("Could not serialize REPL log: {}", exception.getMessage());
    }
  }
ReplState.

Logger class for Repl Events.
ql/src/java/org/apache/hadoop/hive/ql/parse/repl/ReplState.java