private void info(final Supplier<String> messageSupplier) {
        LOGGER.info(messageSupplier);
        taskContextFactory.current().info(messageSupplier);
    }
Gets the earliest meta create time that would be retained by this rule.
stroom-data/stroom-data-retention-impl/src/main/java/stroom/data/retention/impl/DataRetentionPolicyExecutor.java