public final HttpAsyncClientBuilder setConnectionManagerShared(final boolean shared) {
        this.connManagerShared = shared;
        return this;
    }
Defines the connection manager is to be shared by multiple
client instances.
<p>
If the connection manager is shared its life-cycle is expected
to be managed by the caller and it will not be shut down
if the client is closed.
</p>

@param shared defines whether or not the connection manager can be shared
 by multiple clients.

@return this instance.
httpclient5/src/main/java/org/apache/hc/client5/http/impl/async/HttpAsyncClientBuilder.java