private void doRelease() {
            if (isHealthy(this)) {
                // Channel turns out to be healthy. Add it back to the pool.
                addToPool(protocol(), key, this);
            } else {
                // Channel not healthy. Do not add it back to the pool.
            }
        }
Closes all {@link Channel}s managed by this pool.
core/src/main/java/com/linecorp/armeria/client/HttpChannelPool.java