added nullchecks to prevent NPE (#2417)

* added nullchecks to prevent NPE
fixes #2171

* Add test from #2171 and changelog

Co-authored-by: jamesagnew <jamesagnew@gmail.com>

hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/5_4_0/2417-avoid-npe-indexing-timing.yaml

@@ -0,0 +1,5 @@
+---
+type: fix
+issue: 2417
+title: "A NullPointerException was corrected when indexing resources containing an indexed Period field that
+  had a start but not an end defined."

hapi-fhir-jpaserver-base/src/test/java/ca/uhn/fhir/jpa/dao/r4/FhirResourceDaoR4SearchNoFtTest.java

@@ -1496,6 +1496,43 @@ public class FhirResourceDaoR4SearchNoFtTest extends BaseJpaR4Test {
 	}
 
 
+	@Test
+	public void testPeriodWithNoStart() {
+		ServiceRequest serviceRequest = new ServiceRequest();
+
+		Period period = new Period();
+		period.setEnd(new Date());
+		Timing timing = new Timing();
+		timing.setRepeat(new Timing.TimingRepeatComponent().setBounds(period));
+		serviceRequest.setOccurrence(timing);
+
+		// Should not crash
+		myServiceRequestDao.create(serviceRequest);
+
+		runInTransaction(()->{
+			assertEquals(1, myResourceIndexedSearchParamDateDao.findAll().size());
+		});
+	}
+
+	@Test
+	public void testPeriodWithNoEnd() {
+		ServiceRequest serviceRequest = new ServiceRequest();
+		
+		Period period = new Period();
+		period.setStart(new Date());
+		Timing timing = new Timing();
+		timing.setRepeat(new Timing.TimingRepeatComponent().setBounds(period));
+		serviceRequest.setOccurrence(timing);
+
+		// Should not crash
+		myServiceRequestDao.create(serviceRequest);
+
+		runInTransaction(()->{
+			assertEquals(1, myResourceIndexedSearchParamDateDao.findAll().size());
+		});
+	}
+	
+
 	@Test
 	public void testSearchByIdParamInverse() {
 		String id1;

hapi-fhir-jpaserver-searchparam/src/main/java/ca/uhn/fhir/jpa/searchparam/extractor/BaseSearchParamExtractor.java

@@ -1364,8 +1364,12 @@ public abstract class BaseSearchParamExtractor implements ISearchParamExtractor
 					if ("Period".equals(boundsType)) {
 						Date start = extractValueAsDate(myPeriodStartValueChild, bounds.get());
 						Date end = extractValueAsDate(myPeriodEndValueChild, bounds.get());
-						dates.add(start);
+						if (start != null) {
+							dates.add(start);
+						}
+						if (end != null) {
 						dates.add(end);
+						}
 					}
 				}
 			}