@Override
    public void write(int b) throws IOException {
        OutputStream maybe = tee.get();
        if (maybe != null) maybe.write(b);
        original.write(b);
    }
Used to replace System.out and System.err, providing the ability to forward output to an additional sink.

@author jonmv
vespa-osgi-testrunner/src/main/java/com/yahoo/vespa/testrunner/TeeStream.java