Currently the FilterInitializer class, used to filter access to the Hadoop web interfaces, has its main method, initFilter, set to package private. This means that any classes wishing to implement this type must be in the same package. This should be public so FilterInitializers can reside in other packages.
Also, currently all parameters to the FilterInitializer must be provided at compile time (or via a different configuration method). It would be better if the FilterInitalizer::initFilter received a Configuration parameter so it can pull conf values out at run-time. Alternatively, the class could implement Configured, but that seems heavier than is needed at this point.