@Test
    public void shouldGetValueFromSystemProperties() {
        System.setProperty("PROPERTIES_KEY", "42");

        AddHeaderBean header = spy(new AddHeaderBean());

        header.setHeaderName("the-meaning-of-life");
        header.setHeaderValue("PROPERTIES_KEY");
        header.setOverwrite(false);
        header.setApplyTo(ApplyTo.REQUEST);
        header.setValueType(ValueType.SYS);
        config.getAddHeaders().add(header);

        policy.apply(request, mContext, config, mRequestChain);

        assertEquals("42", request.getHeaders().get("the-meaning-of-life"));
        assertEquals(1, request.getHeaders().size());
    }
@author Marc Savy {@literal <msavy@redhat.com>}
plugins/simple-header-policy/src/test/java/io/apiman/plugins/simpleheaderpolicy/SimpleHeaderPolicyTest.java