@Override
    protected ConnPoolByRoute createConnectionPool(long connTTL,
            TimeUnit connTTLTimeUnit) {
        return new NamedConnectionPool(connOperator, connPerRoute, 20, connTTL, connTTLTimeUnit);
    }
A connection manager that uses {@link NamedConnectionPool}, which provides
connection reuse statistics, as its underlying connection pool.

@author awang
ribbon-httpclient/src/main/java/com/netflix/http4/MonitoredConnectionManager.java