public boolean hasMaterial(MaterialConfig materialConfig) {
        for (ConfigRepoConfig c : this) {
            if (c.getRepo().equals(materialConfig)) {
                return true;
            }
        }
        return false;
    }
@Test
    public void shouldReturnFalseThatHasMaterialWhenEmpty() {
        assertThat(repos.isEmpty(), is(true));
        assertThat(repos.hasMaterial(mock(MaterialConfig.class)), is(false));
    }