Fix error message for existing configs in projects that have errors, but were filtered out by filtering prefs. Error message was left off, if there was one.
<?xml version="1.0" encoding="UTF-8"?>
<classpath>
<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/J2SE-1.5"/>
<classpathentry kind="con" path="org.eclipse.pde.core.requiredPlugins"/>
<classpathentry kind="src" path="src"/>
<classpathentry kind="output" path="bin"/>
</classpath>