Gradle的Spring Boot项目 报 class file is not on the classpath错误

大家好！

我用Eclipse Oxygen.3 Release (4.7.3) 导入一个Gradle编译通过的Spring boot项目，现在Eclipse上面报这个错：
The class file is not on the classpath
org.eclipse.core.runtime.CoreException: The class file is not on the classpath

Eclipse需要怎么配置一下能使这个项目通过run as --- Java Application运行起来？
谢谢！