### Question:
Ingest extends AbstractPersistable<Long> { public void addRequiredField(String field) { Assert.hasText(field); if (validRequiredFields.contains(field)) requiredFields.add(field); }  void addRequiredField(String field); Set<String> getRequiredFields(); Set<String> getValidRequiredFields(); CustomRepository getRepository(); void setRepository(CustomRepository repository); Date getLastRun(); void setLastRun(Date lastRun); String getNameOgpRepository(); void setNameOgpRepository(String nameOgpRepository); List<IngestJobStatus> getIngestJobStatuses(); void setIngestJobStatuses(List<IngestJobStatus> ingestJobStatuses); void addJobStatus(IngestJobStatus job); Boolean isScheduled(); void setScheduled(Boolean scheduled); String getName(); void setName(String name); Date getBeginDate(); void setBeginDate(Date beginDate); Frequency getFrequency(); void setFrequency(Frequency frequency); String getUrl(); void setUrl(String url); Boolean getScheduled(); String getActualUrl();  }### Answer:
@Test public void testEmptyRequiredFields() { Ingest ingest = new IngestOGP(); try { ingest.addRequiredField(""); Assert.fail(); } catch (IllegalArgumentException ex) { } try { ingest.addRequiredField(null); Assert.fail(); } catch (IllegalArgumentException ex) { } }