Could not publish to the server.java.lang.NullPointerException

问题描述：

java.lang.NullPointerException
 at org.eclipse.wst.common.componentcore.internal.resources.VirtualResource.getProjectRelativePaths(VirtualResource.java:119)
 at org.eclipse.wst.common.componentcore.internal.resources.VirtualFile.getUnderlyingFiles(VirtualFile.java:104)
 at org.eclipse.wst.common.componentcore.internal.resources.VirtualFile.getUnderlyingResources(VirtualFile.java:93)
 at org.eclipse.wst.common.componentcore.internal.resources.VirtualResource.exists(VirtualResource.java:88)
 at org.eclipse.jst.common.internal.modulecore.util.ManifestUtilities.getNonBinaryComponentManifest(ManifestUtilities.java:124)
 at org.eclipse.jst.common.internal.modulecore.util.ManifestUtilities.getManifest(ManifestUtilities.java:81)
 at org.eclipse.jst.common.internal.modulecore.util.ManifestUtilities.getManifestClasspath(ManifestUtilities.java:147)
 at org.eclipse.jst.j2ee.componentcore.J2EEModuleVirtualComponent.getManifestClasspath(J2EEModuleVirtualComponent.java:248)
 at org.eclipse.jst.j2ee.componentcore.J2EEModuleVirtualComponent.calculateManifestReferences(J2EEModuleVirtualComponent.java:368)
 at org.eclipse.jst.j2ee.componentcore.J2EEModuleVirtualComponent.cacheManifestReferences(J2EEModuleVirtualComponent.java:360)
 at org.eclipse.jst.j2ee.componentcore.J2EEModuleVirtualComponent.getReferences(J2EEModuleVirtualComponent.java:176)
 at org.eclipse.jst.j2ee.componentcore.J2EEModuleVirtualComponent.getReferences(J2EEModuleVirtualComponent.java:214)
 at org.eclipse.jst.j2ee.componentcore.J2EEModuleVirtualComponent.getReferences(J2EEModuleVirtualComponent.java:207)
 at org.eclipse.jst.common.internal.modulecore.AddClasspathLibReferencesParticipant.getReferencedProjectComponentClasspathDependencies(AddClasspathLibReferencesParticipant.java:97)
 at org.eclipse.jst.common.internal.modulecore.AddClasspathLibReferencesParticipant.getChildModules(AddClasspathLibReferencesParticipant.java:138)

解决方案：

1. Removed the project from the workspace
2. Remove .classpath, .project and .settings folder
3. Reimport the project

Maven项目解决：

1. Removed the project from the workspace
2. CMD：mvn eclipse:clean
3. Remove .settings folder
4. CMD：mvn eclipse:eclipse
5. Reimport the project