AppModule.java

@Contribute(ResourceMinimizer.class)
@Primary
public static void overrideGoogleClosureCompiler(MappedConfiguration<String, ResourceMinimizer> conf,
                                                 @Autobuild CustomGoogleClosureMinimizer gcm) {
    conf.override("text/javascript", gcm);
}

CustomGoogleClosureMinimizer.java

public class CustomGoogleClosureMinimizer extends GoogleClosureMinimizer {

    public CustomGoogleClosureMinimizer(Logger logger,
                                        OperationTracker tracker,
                                        AssetChecksumGenerator checksumGenerator,
                                        Request request,
                                        @Symbol(WebResourcesSymbols.COMPILATION_LEVEL) CompilationLevel compilationLevel) {
        super(logger, tracker, checksumGenerator, request, compilationLevel);
    }

    @Override
    protected boolean isEnabled(StreamableResource resource) {

        if (resource.getDescription().endsWith("underscore-1.8.3.js")) {
            return false;
        }

        return super.isEnabled(resource);
    }
}