Resolution:
Description:
=========
The full stack on building the EAR was:

java.lang.Exception: java.lang.NoClassDefFoundError: com/sun/tools/javac/Main
    at com.tibco.cep.studio.core.util.packaging.impl.DefaultRuntimeClassesPackager.close(Unknown Source)
    at com.tibco.cep.studio.core.util.packaging.impl.EMFBarPackager.close(Unknown Source)
    at com.tibco.cep.studio.core.util.packaging.impl.EMFEarPackager.close(Unknown Source)
    at com.tibco.cep.studio.ui.actions.BuildEnterpriseArchiveAction.runBuildArchive(Unknown Source)
    at com.tibco.cep.studio.ui.actions.BuildEnterpriseArchiveAction.access$0(Unknown Source)
    at com.tibco.cep.studio.ui.actions.BuildEnterpriseArchiveAction$BuildArchiveJob.run(Unknown Source)
    at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)
Caused by: java.lang.NoClassDefFoundError: com/sun/tools/javac/Main
    at com.tibco.cep.studio.parser.codegen.CodeGenHelper.compileSourceFiles(Unknown Source)
    at com.tibco.cep.studio.parser.codegen.BaseGenerator.compileSource(Unknown Source)
    at com.tibco.cep.studio.parser.codegen.BaseGenerator.compileSource(Unknown Source)
    at com.tibco.cep.studio.parser.codegen.BaseGenerator.compile(Unknown Source)
    ... 7 more

Environment:
=========
Windows 7; BE 4.0.2

Cause:
=========
Bad .beproject file.  Different from the svn version.

Resolution:
=========
.beproject file tools.jar entry was missing.  Added:

&ltcoreInternalLibEntries entryType="Core" path="C:\tibco2\tibcojre\1.6.0\lib\tools.jar" timestamp="1327552328000"/>