我从github查看了spring security的源码，我想在samples目录下运行“contacts”示例（samples目录有一个名为contacts-xml的子目录），我尝试了按照http://docs的方法。 spring.io/spring-security/site/build.html，我通过命令成功运行了cas demo
毕业证
它有效。
但是当我尝试
gradle jettyRun
在contacts-xml 目录中，我收到一条错误消息
nine@nine:~/codes/spring-security/samples/contacts-xml$ gradle jettyRun
:buildSrc:compileJava UP-TO-DATE
:buildSrc:compileGroovy
:buildSrc:processResources UP-TO-DATE
:buildSrc:classes
:buildSrc:jar
:buildSrc:assemble
:buildSrc:compileTestJava UP-TO-DATE
:buildSrc:compileTestGroovy UP-TO-DATE
:buildSrc:processTestResources UP-TO-DATE
:buildSrc:testClasses UP-TO-DATE
:buildSrc:test UP-TO-DATE
:buildSrc:check UP-TO-DATE
:buildSrc:build
The ConfigurationContainer.add() method has been deprecated and is scheduled to be removed in Gradle 2.0. Please use the create() method instead.
The TaskContainer.add() method has been deprecated and is scheduled to be removed in Gradle 2.0. Please use the create() method instead.
The Test.testResultsDir property has been deprecated and is scheduled to be removed in Gradle 2.0. Please use the Test.getReports().getJunitXml().setDestination() property instead.
The Test.testReportDir property has been deprecated and is scheduled to be removed in Gradle 2.0. Please use the Test.getReports().getHtml().getDestination() property instead.
'appEngineSdkRoot' must be set in gradle.properties
2013-10-15 10:01:59.832:INFO::Logging to STDERR via org.mortbay.log.StdErrLog
FAILURE: Could not determine which tasks to execute.
* What went wrong:
**Task 'jettyRun' not found in project ':spring-security-samples-contacts-xml'.**
* Try:
Run gradle tasks to get a list of available tasks.
**BUILD FAILED**
我错过了什么吗？