Pedigree { @JsonIgnore public Set<String> getIdentifiers() { return individualsById.keySet(); } private  Pedigree(Collection<Individual> individuals); static Pedigree of(Collection<Individual> individuals); static Pedigree of(Individual... individuals); static Pedigree justProband(String id); static Pedigree empty(); @JsonIgnore boolean containsId(String id); @JsonIgnore Individual getIndividualById(String individualId); Set<Individual> getIndividuals(); @JsonIgnore Set<String> getIdentifiers(); @JsonIgnore int size(); @JsonIgnore boolean isEmpty(); @JsonIgnore int numFamilies(); @Override boolean equals(Object o); @Override int hashCode(); @Override String toString();  }
@Test public void testGetIdentifiers() { Pedigree instance = Pedigree.of(PROBAND, MOTHER, FATHER); assertThat(instance.getIdentifiers(), equalTo(ImmutableSet.of(PROBAND.getId(), MOTHER.getId(), FATHER.getId()))); }