Importing "java.util.TreeMap" to a package causes java.lang.NullPointerException at SuggestionCompletionEngineBuilder

Issue

• Importing java.util.TreeMap to a package causes java.lang.NullPointerException at SuggestionCompletionEngineBuilder . This causes the following ERROR [1][2] to appear on the BRM (Business Rules Manager) screen as a pop-up window (screenshot attached Screenshot-JBoss BRMS_issue.png).

[1] "Unable to get content assistance for this rule." 
[2] "Unable to validate package configuration (eg, DSLs, models) for [defaultPackage]. Suggestion completions may not operate correctly for graphical editors for this package."

The server.log file logs the following ERROR [3]

[3] 2012-05-07 22:37:15,049 ERROR [org.drools.guvnor.server.RepositoryServiceServlet] (http-xx.xx.xx.xx-8080-4) Service method 'public abstract org.drools.ide.common.client.modeldriven.SuggestionCompletionEngine org.drools.guvnor.client.rpc.RepositoryService.loadSuggestionCompletionEngine(java.lang.String) throws com.google.gwt.user.client.rpc.SerializationException' threw an unexpected exception: java.lang.NullPointerException
java.lang.NullPointerException
    at org.drools.ide.common.server.util.SuggestionCompletionEngineBuilder.obtainGenericType(SuggestionCompletionEngineBuilder.java:209)
    at org.drools.ide.common.server.util.SuggestionCompletionEngineBuilder.getInstance(SuggestionCompletionEngineBuilder.java:274)
    at org.drools.ide.common.server.rules.SuggestionCompletionLoader.loadClassFields(SuggestionCompletionLoader.java:701)
    at org.drools.ide.common.server.rules.SuggestionCompletionLoader.addFactType(SuggestionCompletionLoader.java:584)
    at org.drools.ide.common.server.rules.SuggestionCompletionLoader.populateModelInfo(SuggestionCompletionLoader.java:319)
    at org.drools.ide.common.server.rules.SuggestionCompletionLoader.populateEngineBuilder(SuggestionCompletionLoader.java:223)
    at org.drools.ide.common.server.rules.SuggestionCompletionLoader.processPackageHeader(SuggestionCompletionLoader.java:217)
    at org.drools.ide.common.server.rules.SuggestionCompletionLoader.getSuggestionEngine(SuggestionCompletionLoader.java:185)
    at org.drools.guvnor.server.util.BRMSSuggestionCompletionLoader.getSuggestionEngine(BRMSSuggestionCompletionLoader.java:63)
    at org.drools.guvnor.server.util.BRMSSuggestionCompletionLoader.getSuggestionEngine(BRMSSuggestionCompletionLoader.java:70)
    at org.drools.guvnor.server.SuggestionCompletionEngineLoaderInitializer.loadFor(SuggestionCompletionEngineLoaderInitializer.java:42)
    at org.drools.guvnor.server.ServiceImplementation.loadSuggestionCompletionEngine(ServiceImplementation.java:463)
        .........