Seems that classes with Rebuild plugin dependencies are not marked as "optional".

Feb 15, 2014 2:27:50 PM hudson.ExtensionFinder$Sezpoz _find
WARNING: Failed to load hudson.plugins.project_inheritance.projects.rebuild.RebuildValidatorSuppressor
java.lang.InstantiationException: file:/C:/Users/nenashev/Documents/Jenkins/contrib/ownership-plugin/work/plugins/project-inheritance/WEB-INF/classes/META-INF/annotations/hudson.Extension might need to be rebuilt: java.lang.ClassNotFoundException: hudson.plugins.project_inheritance.projects.rebuild.RebuildValidatorSuppressor
at net.java.sezpoz.IndexItem.element(IndexItem.java:144)
at hudson.ExtensionFinder$Sezpoz._find(ExtensionFinder.java:611)
at hudson.ExtensionFinder$Sezpoz.find(ExtensionFinder.java:600)
at hudson.ExtensionFinder$GuiceFinder.<init>(ExtensionFinder.java:259)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at java.lang.Class.newInstance(Class.java:374)
at net.java.sezpoz.IndexItem.instance(IndexItem.java:181)
at hudson.ExtensionFinder$Sezpoz._find(ExtensionFinder.java:625)
at hudson.ExtensionFinder$Sezpoz.find(ExtensionFinder.java:600)
at hudson.ExtensionFinder._find(ExtensionFinder.java:151)
at hudson.ClassicPluginStrategy.findComponents(ClassicPluginStrategy.java:318)
at hudson.ExtensionList.load(ExtensionList.java:295)
at hudson.ExtensionList.ensureLoaded(ExtensionList.java:248)
at hudson.ExtensionList.iterator(ExtensionList.java:138)
at hudson.ClassicPluginStrategy.findComponents(ClassicPluginStrategy.java:311)
at hudson.ExtensionList.load(ExtensionList.java:295)
at hudson.ExtensionList.ensureLoaded(ExtensionList.java:248)
at hudson.ExtensionList.get(ExtensionList.java:153)
at hudson.PluginManager$PluginUpdateMonitor.getInstance(PluginManager.java:1066)
at hudson.maven.PluginImpl.init(PluginImpl.java:54)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at hudson.init.InitializerFinder.invoke(InitializerFinder.java:120)
at hudson.init.InitializerFinder$TaskImpl.run(InitializerFinder.java:184)
at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:259)
at jenkins.model.Jenkins$7.runTask(Jenkins.java:888)
at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:187)
at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:94)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)
Caused by: java.lang.ClassNotFoundException: hudson.plugins.project_inheritance.projects.rebuild.RebuildValidatorSuppressor
at hudson.PluginManager$UberClassLoader.findClass(PluginManager.java:942)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
at net.java.sezpoz.IndexItem.element(IndexItem.java:134)
... 35 more