public Builder setProtocolUpgradeEnabled(final boolean protocolUpgradeEnabled) {
            this.protocolUpgradeEnabled = protocolUpgradeEnabled;
            return this;
        }
Determines whether the client server should automatically attempt to upgrade
to a safer or a newer version of the protocol, whenever possible.
<p>
Presently supported: HTTP/1.1 TLS upgrade
</p>
<p>
Default: {@code true}
</p>

@return this instance.
@since 5.4
httpclient5/src/main/java/org/apache/hc/client5/http/config/RequestConfig.java