@BeforeEach
    public void setUpStreams() {
        oldOut = System.out;
        oldErr = System.err;
        System.setOut(new PrintStream(outContent));
        System.setErr(new PrintStream(errContent));
    }
Test class for {@link DocumentRetriever}

@author bjorncs
vespaclient-java/src/test/java/com/yahoo/vespaget/DocumentRetrieverTest.java