28.7. 使用系统属性
当将 useSystemProperties 设置为 true 时，HTTP 客户端将查找以下系统属性，它将使用它：
- ssl.TrustManagerFactory.algorithm
- javax.net.ssl.trustStoreType
- javax.net.ssl.trustStore
- javax.net.ssl.trustStoreProvider
- javax.net.ssl.trustStorePassword
- java.home
- ssl.KeyManagerFactory.algorithm
- javax.net.ssl.keyStoreType
- javax.net.ssl.keyStore
- javax.net.ssl.keyStoreProvider
- javax.net.ssl.keyStorePassword
- http.proxyHost
- http.proxyPort
- http.nonProxyHosts
- http.keepAlive
- http.maxConnections
