Classpath entry org.maven.ide.eclipse.MAVEN2_CLASSPATH_CONTAINER will not be exported or published

sometimes when importing a maven project in eclipse, i get the following error:

Classpath entry org.maven.ide.eclipse.MAVEN2_CLASSPATH_CONTAINER will not be exported or published. Runtime ClassNotFoundExceptions may result

.

although the classpath file on the svn repo contains the maven dependencies entry:

<classpathentry kind="con" path="org.maven.ide.eclipse.MAVEN2_CLASSPATH_CONTAINER">
    		<attributes>
    			<attribute name="org.eclipse.jst.component.dependency" value="/WEB-INF/lib"/>
    		</attributes>
    	</classpathentry>

i know the workaround to solve the issue by going to project deployment assembly and adding maven dependencies manually (which will add the entry above again !), but i am curious to know, why such error is generated, although classpath contains the dependencies entry ?
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