Taxonomy find method must use '' instead of null

src/main/java/org/genesys2/server/service/impl/TaxonomyServiceImpl.java

@@ -150,12 +150,12 @@ public class TaxonomyServiceImpl implements TaxonomyService {
 
 	@Override
 	public long getTaxonomy2Id(String genus) {
-		return taxonomy2Repository.findByGenusAndSpeciesAndSpAuthorAndSubtaxaAndSubtAuthor(genus, "sp.", null, null, null).getId();
+		return taxonomy2Repository.findByGenusAndSpeciesAndSpAuthorAndSubtaxaAndSubtAuthor(genus, "sp.", "", "", "").getId();
 	}
 
 	@Override
 	public long getTaxonomy2Id(String genus, String species) {
-		Taxonomy2 tax = taxonomy2Repository.findByGenusAndSpeciesAndSpAuthorAndSubtaxaAndSubtAuthor(genus, species, null, null, null);
+		Taxonomy2 tax = taxonomy2Repository.findByGenusAndSpeciesAndSpAuthorAndSubtaxaAndSubtAuthor(genus, species, "", "", "");
 		return tax.getId();
 	}