使用Eclipse Marketplace 安装CheckStyle Plugin的时候，有时候会出现不能安装的错误：
at java.base/sun.security.validator.PKIXValidator.(PKIXValidator.java:89)
at java.base/sun.security.validator.Validator.getInstance(Validator.java:181)
at java.base/sun.security.ssl.X509TrustManagerImpl.getValidator(X509TrustManagerImpl.java:330)
at java.base/sun.security.ssl.X509TrustManagerImpl.checkTrustedInit(X509TrustManagerImpl.java:180)
at java.base/sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:192)
at java.base/sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:133)
这个时候可以用浏览器打开网站，https://checkstyle.org/eclipse-cs/， 导出证书，然后用Keytool 把证书导入到JDK就可以啦：
keytool -import -alias style -keystore xxx\jdk1.8.0_91\jre\lib\security\cacerts -file xxx\jdk1.8.0_91\jre\lib\security\checkstyle.cer
另外也可以从下边的网址下载ZIP文件安装：
https://bintray.com/eclipse-cs/eclipse-cs/update-site-archive/8.27.0
https://checkstyle.org/eclipse-cs/#!/custom-config