merger.merge(null, null, null);

        PersistedToolchains pt = new PersistedToolchains();
        merger.merge(pt, null, null);
        merger.merge(null, pt, null);
    }

    @Test
    void testMergeJdk() throws Exception {
        try (InputStream isDominant = MavenToolchainMergerTest.class.getResourceAsStream("toolchains-jdks.xml");