public PackageDefinition find(final String id) {
        return stream().filter(packageDefinition -> packageDefinition.getId().equals(id)).findFirst().orElse(null);
    }
@Test
    public void shouldReturnNullIfNoMatchingPkgFound() throws Exception {
        Packages packages = new Packages();
        assertThat(packages.find("id2"), is(nullValue()));
    }