public final HttpAsyncClientBuilder evictExpiredConnections() {
        evictExpiredConnections = true;
        return this;
    }
Makes this instance of HttpClient proactively evict expired connections from the
connection pool using a background thread.
<p>
One MUST explicitly close HttpClient with {@link CloseableHttpAsyncClient#close()} in order
to stop and release the background thread.
<p>
Please note this method has no effect if the instance of HttpClient is configured to
use a shared connection manager.

@see #setConnectionManagerShared(boolean)
@see ConnPoolControl#closeExpired()

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