升级android 3.0

最近android studio 升级了，对于以前的项目编译后出现了下面的错误，

Execution failed for task ':app:javaPreCompileDebug'.

> Annotation processors must be explicitly declared now.  The following dependencies on the compile classpath are found to contain annotation processor.  Please add them to the annotationProcessor configuration.

- butterknife-7.0.1.jar (com.jakewharton:butterknife:7.0.1)

Alternatively, set android.defaultConfig.javaCompileOptions.annotationProcessorOptions.includeCompileClasspath = true to continue with previous behavior.  Note that this option is deprecated and will be removed in the future.

See https://developer.android.com/r/tools/annotation-processor-error-message.html for more details.

解决方法就是在gradle 里的 android  --》defaultConfig 里添加如下设置