@Nullable
        @Override
        public final Object getMessage(RequestLog log) {
            if (condition != null &&
                !condition.apply(log.responseHeaders())) {
                return null;
            }
            return getMessage0(log);
        }
An abstract class to support a condition whether a log component is applied or not.
core/src/main/java/com/linecorp/armeria/server/logging/AccessLogComponent.java