should be using JavaSE-1.6 VM, and .classpath, codegen.targetPlatform, compliance and source should also all be 1.6
<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.2"?>
<plugin>
<extension-point id="featureUseTracker" name="Feature Usage Tracker" schema="schema/featureUseTracker.exsd"/>
</plugin>