@Test
public void getGeneSymbol() {

    assertThat(EMPTY_GENE_IDENTIFIER.getGeneSymbol(), equalTo(GeneIdentifier.EMPTY_FIELD));
    GeneIdentifier instance = GeneIdentifier.builder()
            .geneSymbol("ABC1")
            .build();
    assertThat(instance.getGeneSymbol(), equalTo("ABC1"));
}