It's confirmed as Selenium bug. Endpoints for contexts were accidentally deleted. Working on a PR to Selenium
https://github.com/appium/java-client/issues/36
回滚到 2.41.0 吧
<dependency>
<groupId>org.seleniumhq.selenium</groupId>
<artifactId>selenium-java</artifactId>
<version>2.41.0</version>
<scope>test</scope>
</dependency>