Fix #2427: Arxiv fetcher works with prefix

CHANGELOG.md

@@ -24,6 +24,7 @@ We refer to [GitHub issues](https://github.com/JabRef/jabref/issues) by using `#
 - We fixed an issue where groups containing brackets were not working properly. Fixes [#2394](https://github.com/JabRef/jabref/issues/2394).
 - We fixed issues with the [timestamp](http://help.jabref.org/en/TimeStamp) field. However, clearing with the clear button is not possible if timestamp format does not match the current settings. Fixes [#2403](https://github.com/JabRef/jabref/issues/2403).
 - Fixes [#2406](https://github.com/JabRef/jabref/issues/2406) so that the integrity check filter works again
+- The ArXiv fetcher also accepts identifiers that include the "arXiv:" prefix. Fixes [#2427](https://github.com/JabRef/jabref/issues/2427).
 - Closing of subtrees in the groups panel using "close subtree" is working again. Fixes [#2319](https://github.com/JabRef/jabref/issues/2319).
 - The proxy settings are now also applied to HTTPS connections. Fixes [#2249](https://github.com/JabRef/jabref/issues/2249).
 

src/main/java/net/sf/jabref/logic/importer/fetcher/ArXiv.java

@@ -107,6 +107,10 @@ private Optional<ArXivEntry> searchForEntry(String searchQuery) throws FetcherEx
     }
 
     private Optional<ArXivEntry> searchForEntryById(String identifier) throws FetcherException {
+        identifier = identifier.replace("arxiv:", "");
+        identifier = identifier.replace("arXiv:", "");
+        identifier = identifier.replace("arxiv", "");
+        identifier = identifier.replace("arXiv", "");
         List<ArXivEntry> entries = queryApi("", Collections.singletonList(identifier), 0, 1);
         if (entries.size() == 1) {
             return Optional.of(entries.get(0));

src/test/java/net/sf/jabref/logic/importer/fetcher/ArXivTest.java

@@ -75,6 +75,14 @@ public void findByEprint() throws IOException {
         assertEquals(Optional.of(new URL("http://arxiv.org/pdf/1603.06570v1")), finder.findFullText(entry));
     }
 
+    @Test
+    // Test for https://github.com/JabRef/jabref/issues/2427
+    public void findByEprintWithPrefix() throws IOException {
+        entry.setField("eprint", "arXiv:1603.06570");
+
+        assertEquals(Optional.of(new URL("http://arxiv.org/pdf/1603.06570v1")), finder.findFullText(entry));
+    }
+
     @Test
     public void findByEprintWithUnknownDOI() throws IOException {
         entry.setField("doi", "10.1529/unknown");
@@ -138,6 +146,12 @@ public void searchEntryByIdWith4Digits() throws Exception {
         assertEquals(Optional.of(sliceTheoremPaper), finder.performSearchById("1405.2249"));
     }
 
+    @Test
+    // Test for https://github.com/JabRef/jabref/issues/2427
+    public void searchEntryByIdWith4DigitsAndPrefix() throws Exception {
+        assertEquals(Optional.of(sliceTheoremPaper), finder.performSearchById("arXiv:1405.2249"));
+    }
+
     @Test
     public void searchEntryByIdWith5Digits() throws Exception {
         assertEquals(Optional.of(