Fix Medline tests (#5774)

- wait between calls to avoid 403
- remove assertion of entry not returned anymore

src/main/java/org/jabref/logic/importer/IdBasedParserFetcher.java

@@ -81,7 +81,7 @@ default Optional<BibEntry> performSearchById(String identifier) throws FetcherEx
         } catch (URISyntaxException e) {
             throw new FetcherException("Search URI is malformed", e);
         } catch (IOException e) {
-            // TODO: Catch HTTP Response 401 errors and report that user has no rights to access resource
+            // TODO: Catch HTTP Response 401 errors and report that user has no rights to access resource. It might be that there is an UnknownHostException (eutils.ncbi.nlm.nih.gov cannot be resolved).
             throw new FetcherException("A network error occurred", e);
         } catch (ParseException e) {
             throw new FetcherException("An internal parser error occurred", e);

src/test/java/org/jabref/logic/importer/fetcher/MedlineFetcherTest.java

@@ -24,7 +24,10 @@ public class MedlineFetcherTest {
     private BibEntry entryWijedasa, entryEndharti, bibEntryIchikawa, bibEntrySari;
 
     @BeforeEach
-    public void setUp() {
+    public void setUp() throws InterruptedException {
+        // pause between runs to avoid 403 and 429 at Medline
+        Thread.sleep(1000);
+
         fetcher = new MedlineFetcher();
 
         entryWijedasa = new BibEntry();
@@ -167,7 +170,6 @@ public void testMultipleEntries() throws Exception {
         entryList.forEach(entry -> entry.clearField(StandardField.ABSTRACT)); //Remove abstract due to copyright);
         assertEquals(50, entryList.size());
         assertTrue(entryList.contains(bibEntryIchikawa));
-        assertTrue(entryList.contains(bibEntrySari));
     }
 
     @Test