VIVO-869 Don't operate on null URIs.

If a UriFinder finds a null URI, issue a warning message. If a null URI is submitted to UpdateUrisTask, ignore it.

webapp/src/edu/cornell/mannlib/vitro/webapp/searchindex/indexing/IndexingUriFinderListBasic.java

@@ -9,12 +9,18 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
 import com.hp.hpl.jena.rdf.model.Statement;
 
 /**
  * The basic implementation.
  */
 public class IndexingUriFinderListBasic implements IndexingUriFinderList {
+	private static final Log log = LogFactory
+			.getLog(IndexingUriFinderListBasic.class);
+
 	private final List<IndexingUriFinder> finders;
 
 	public IndexingUriFinderListBasic(
@@ -40,7 +46,14 @@ public class IndexingUriFinderListBasic implements IndexingUriFinderList {
 	public Set<String> findAdditionalUris(Statement stmt) {
 		Set<String> uris = new HashSet<>();
 		for (IndexingUriFinder uriFinder : finders) {
-			uris.addAll(uriFinder.findAdditionalURIsToIndex(stmt));
+			List<String> additions = uriFinder.findAdditionalURIsToIndex(stmt);
+			for (String addition : additions) {
+				if (addition == null) {
+					log.warn("Finder " + uriFinder + " returned a null URI.");
+				} else {
+					uris.add(addition);
+				}
+			}
 		}
 		return uris;
 	}

webapp/src/edu/cornell/mannlib/vitro/webapp/searchindex/tasks/UpdateUrisTask.java

@@ -83,6 +83,8 @@ public class UpdateUrisTask implements Task {
 			if (isInterrupted()) {
 				log.info("Interrupted: " + status.getSearchIndexerStatus());
 				break;
+			} else if (uri == null) {
+				// Nothing to do
 			} else {
 				Individual ind = getIndividual(uri);
 				if (ind == null) {