eclipse 插件开发，报错No property tester contributes a property....

ENTRY org.eclipse.ui.navigator 4 2 2012-06-12 10:06:54.431
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.ui.navigator".
!STACK 1
org.eclipse.core.runtime.CoreException: No property tester contributes a property com.sunline.flow.ide.project.navigator.tester.SubSystemPropertyTester to type class org.eclipse.core.internal.resources.Project

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检查了半天，原来是tester的type属性配置为IFolder，而鼠标选择的是工程，应该配置IProject或者IResource。

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