public static void calculateLastModified(ResearcherUrls researcherUrls) { if (researcherUrls != null && researcherUrls.getResearcherUrls() != null && !researcherUrls.getResearcherUrls().isEmpty()) { LastModifiedDate latest = null; for (ResearcherUrl researcherUrl : researcherUrls.getResearcherUrls()) { if (researcherUrl.getLastModifiedDate() != null && researcherUrl.getLastModifiedDate().after(latest)) { latest = researcherUrl.getLastModifiedDate(); } } researcherUrls.setLastModifiedDate(latest); } }