@Override
    public boolean isAcquirable() {
        // responseDecoder and keepAliveHandler are set before this session is added to the pool.
        assert responseDecoder != null;
        return isAcquirable(responseDecoder.keepAliveHandler());
    }
{@code true} if an {@link Http2Settings} has been received from the remote endpoint.
core/src/main/java/com/linecorp/armeria/client/HttpSessionHandler.java