Library Sources are not available in SuperDevMode

[confile]

I created a demo project here: https://github.com/confile/Realtime-JSON-Test

It compile with GWT compile without any problems from Eclipse. When I run the app in SuperDevMode the first compile failed with the following errors:

        Compiling 1 permutation

            Compiling permutation 0...

            [ERROR] An internal compiler exception occurred

com.google.gwt.dev.jjs.InternalCompilerException: Unexpected error during visit.

    at com.google.gwt.dev.jjs.ast.JVisitor.translateException(JVisitor.java:121)

    at com.google.gwt.dev.jjs.ast.JVisitor.accept(JVisitor.java:140)

    at com.google.gwt.dev.jjs.ast.JVisitor.accept(JVisitor.java:132)

    at com.google.gwt.dev.jjs.impl.Devirtualizer.getStaticImpl(Devirtualizer.java:562)

    at com.google.gwt.dev.jjs.impl.Devirtualizer.access$400(Devirtualizer.java:75)

    at com.google.gwt.dev.jjs.impl.Devirtualizer$RewriteVirtualDispatches.ensureDevirtualVersionExists(Devirtualizer.java:184)

    at com.google.gwt.dev.jjs.impl.Devirtualizer$RewriteVirtualDispatches.endVisit(Devirtualizer.java:101)

    at com.google.gwt.dev.jjs.ast.JMethod.traverse(JMethod.java:580)

    at com.google.gwt.dev.jjs.ast.JModVisitor$ListContextImmutable.traverse(JModVisitor.java:183)

    at com.google.gwt.dev.jjs.ast.JModVisitor.acceptWithInsertRemoveImmutable(JModVisitor.java:355)

    at com.google.gwt.dev.jjs.ast.JInterfaceType.traverse(JInterfaceType.java:75)

    at com.google.gwt.dev.jjs.ast.JModVisitor.traverse(JModVisitor.java:380)

    at com.google.gwt.dev.jjs.ast.JModVisitor.accept(JModVisitor.java:292)

    at com.google.gwt.dev.jjs.ast.JModVisitor.accept(JModVisitor.java:284)

    at com.google.gwt.dev.jjs.ast.JProgram.visitModuleTypes(JProgram.java:1192)

    at com.google.gwt.dev.jjs.ast.JProgram.traverse(JProgram.java:1156)

    at com.google.gwt.dev.jjs.ast.JModVisitor.traverse(JModVisitor.java:380)

    at com.google.gwt.dev.jjs.ast.JModVisitor.accept(JModVisitor.java:292)

    at com.google.gwt.dev.jjs.ast.JModVisitor.accept(JModVisitor.java:284)

    at com.google.gwt.dev.jjs.impl.Devirtualizer.execImpl(Devirtualizer.java:320)

    at com.google.gwt.dev.jjs.impl.Devirtualizer.exec(Devirtualizer.java:218)

    at com.google.gwt.dev.jjs.MonolithicJavaToJavaScriptCompiler$MonolithicPermutationCompiler.normalizeSemantics(MonolithicJavaToJavaScriptCompiler.java:95)

    at com.google.gwt.dev.jjs.JavaToJavaScriptCompiler$PermutationCompiler.compilePermutation(JavaToJavaScriptCompiler.java:290)

    at com.google.gwt.dev.jjs.MonolithicJavaToJavaScriptCompiler.compilePermutation(MonolithicJavaToJavaScriptCompiler.java:296)

    at com.google.gwt.dev.jjs.UnifiedAst.compilePermutation(UnifiedAst.java:143)

    at com.google.gwt.dev.CompilePerms.compile(CompilePerms.java:197)

    at com.google.gwt.dev.ThreadedPermutationWorkerFactory$ThreadedPermutationWorker.compile(ThreadedPermutationWorkerFactory.java:50)

    at com.google.gwt.dev.PermutationWorkerFactory$Manager$WorkerThread.run(PermutationWorkerFactory.java:74)

    at java.lang.Thread.run(Thread.java:745)

Caused by: java.lang.NullPointerException

    at com.google.gwt.dev.jjs.ast.JVisitor.accept(JVisitor.java:137)

    ... 27 more

               [ERROR] <no source info>: <source info not available>

               [ERROR] at JsonElement.java(19): public abstract JsonElement clear();

                  com.google.gwt.dev.jjs.ast.JMethod

               [ERROR] at JsonElement.java(18): interface JsonElement extends Serializable 

                  com.google.gwt.dev.jjs.ast.JInterfaceType

               [ERROR] at Unknown(0): <JProgram>

                  com.google.gwt.dev.jjs.ast.JProgram

            [ERROR] Unrecoverable exception, shutting down

com.google.gwt.core.ext.UnableToCompleteException: (see previous log entries)

    at com.google.gwt.dev.javac.CompilationProblemReporter.logAndTranslateException(CompilationProblemReporter.java:106)

    at com.google.gwt.dev.jjs.JavaToJavaScriptCompiler$PermutationCompiler.compilePermutation(JavaToJavaScriptCompiler.java:367)

    at com.google.gwt.dev.jjs.MonolithicJavaToJavaScriptCompiler.compilePermutation(MonolithicJavaToJavaScriptCompiler.java:296)

    at com.google.gwt.dev.jjs.UnifiedAst.compilePermutation(UnifiedAst.java:143)

    at com.google.gwt.dev.CompilePerms.compile(CompilePerms.java:197)

    at com.google.gwt.dev.ThreadedPermutationWorkerFactory$ThreadedPermutationWorker.compile(ThreadedPermutationWorkerFactory.java:50)

    at com.google.gwt.dev.PermutationWorkerFactory$Manager$WorkerThread.run(PermutationWorkerFactory.java:74)

    at java.lang.Thread.run(Thread.java:745)

            [ERROR] Not all permutation were compiled , completed (0/1)

      [WARN] recompile failed

      [WARN] continuing to serve previous version

The library uses the <super-source path="super" /> tag. From the GWT documentation I found (http://www.gwtproject.org/doc/latest/DevGuideOrganizingProjects.html)

" In development mode, the native JRE classes always supercede classes compiled from source."

This is a problem because I cannot use the lib in SuperDevMode.

Is there any way to fix this?