@Test
public void getEnsemblId() {

    assertThat(EMPTY_GENE_IDENTIFIER.getEnsemblId(), equalTo(GeneIdentifier.EMPTY_FIELD));
    GeneIdentifier instance = GeneIdentifier.builder()
            .ensemblId("ensemble")
            .build();
    assertThat(instance.getEnsemblId(), equalTo("ensemble"));
}