Requality

При попытке закрыть проект, в котором есть импортированный документ, возникает ошибка:
eclipse.buildId=4.6.3.M20170301-0400
java.version=1.8.0_161
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=en_US
Framework arguments: -product com.unitesk.requality.product.product -perspective com.unitesk.requality.main.perspective -product com.unitesk.requality.product.product -perspective com.unitesk.requality.main.perspective
Command-line arguments: -os win32 -ws win32 -arch x86 -product com.unitesk.requality.product.product -perspective com.unitesk.requality.main.perspective -data file:/C:/Users/nicke/workspace_bundle2/ -product com.unitesk.requality.product.product -perspective com.unitesk.requality.main.perspective

org.eclipse.core.jobs
Error
Wed Apr 18 16:57:46 MSK 2018
An internal error occurred during: "Close Project".

java.lang.RuntimeException: Illegal attempt to modify an immutable tree.
at org.eclipse.core.internal.dtree.AbstractDataTree.handleImmutableTree(AbstractDataTree.java:248)
at org.eclipse.core.internal.dtree.DeltaDataTree.deleteChild(DeltaDataTree.java:379)
at org.eclipse.core.internal.watson.ElementTree.deleteElement(ElementTree.java:247)
at org.eclipse.core.internal.resources.Workspace.deleteResource(Workspace.java:1426)
at org.eclipse.core.internal.resources.Project.internalClose(Project.java:604)
at org.eclipse.core.internal.resources.Project.close(Project.java:194)
at org.eclipse.ui.actions.CloseResourceAction.invokeOperation(CloseResourceAction.java:135)
at org.eclipse.ui.actions.WorkspaceAction.execute(WorkspaceAction.java:156)
at org.eclipse.ui.actions.WorkspaceAction$1.runInWorkspace(WorkspaceAction.java:456)
at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:39)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)