diff --git a/src/main/java/org/jabref/logic/importer/WebFetchers.java b/src/main/java/org/jabref/logic/importer/WebFetchers.java
index bbaf5d6e73fa..69b0dbb692df 100644
--- a/src/main/java/org/jabref/logic/importer/WebFetchers.java
+++ b/src/main/java/org/jabref/logic/importer/WebFetchers.java
@@ -28,9 +28,6 @@
 import org.jabref.logic.importer.fetcher.IEEE;
 import org.jabref.logic.importer.fetcher.INSPIREFetcher;
 import org.jabref.logic.importer.fetcher.IacrEprintFetcher;
-import org.jabref.logic.importer.fetcher.isbntobibtex.DoiToBibtexConverterComIsbnFetcher;
-import org.jabref.logic.importer.fetcher.isbntobibtex.EbookDeIsbnFetcher;
-import org.jabref.logic.importer.fetcher.isbntobibtex.IsbnFetcher;
 import org.jabref.logic.importer.fetcher.LibraryOfCongress;
 import org.jabref.logic.importer.fetcher.MathSciNet;
 import org.jabref.logic.importer.fetcher.MedlineFetcher;
@@ -44,6 +41,9 @@
 import org.jabref.logic.importer.fetcher.SpringerLink;
 import org.jabref.logic.importer.fetcher.TitleFetcher;
 import org.jabref.logic.importer.fetcher.ZbMATH;
+import org.jabref.logic.importer.fetcher.isbntobibtex.DoiToBibtexConverterComIsbnFetcher;
+import org.jabref.logic.importer.fetcher.isbntobibtex.EbookDeIsbnFetcher;
+import org.jabref.logic.importer.fetcher.isbntobibtex.IsbnFetcher;
 import org.jabref.logic.importer.fileformat.PdfMergeMetadataImporter;
 import org.jabref.model.database.BibDatabaseContext;
 import org.jabref.model.entry.field.Field;
@@ -120,7 +120,7 @@ public static SortedSet<SearchBasedFetcher> getSearchBasedFetchers(ImportFormatP
         set.add(new SemanticScholar());
         set.add(new ResearchGate(importFormatPreferences));
         set.add(new BiodiversityLibrary(importerPreferences));
-      return set;
+        return set;
     }
 
     /**
diff --git a/src/main/java/org/jabref/logic/importer/fetcher/isbntobibtex/DoiToBibtexConverterComIsbnFetcher.java b/src/main/java/org/jabref/logic/importer/fetcher/isbntobibtex/DoiToBibtexConverterComIsbnFetcher.java
index 58a2f5c2a576..cf3721eab658 100644
--- a/src/main/java/org/jabref/logic/importer/fetcher/isbntobibtex/DoiToBibtexConverterComIsbnFetcher.java
+++ b/src/main/java/org/jabref/logic/importer/fetcher/isbntobibtex/DoiToBibtexConverterComIsbnFetcher.java
@@ -1,9 +1,13 @@
 package org.jabref.logic.importer.fetcher.isbntobibtex;
 
-import kong.unirest.json.JSONArray;
-import kong.unirest.json.JSONException;
-import kong.unirest.json.JSONObject;
-import org.apache.http.client.utils.URIBuilder;
+import java.net.MalformedURLException;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
 import org.jabref.logic.importer.FetcherException;
 import org.jabref.logic.importer.ImportFormatPreferences;
 import org.jabref.logic.importer.ParseException;
@@ -15,16 +19,13 @@
 import org.jabref.model.entry.types.StandardEntryType;
 import org.jabref.model.strings.StringUtil;
 
-import java.net.MalformedURLException;
-import java.net.URISyntaxException;
-import java.net.URL;
-import java.util.Collections;
-import java.util.List;
-import java.util.stream.IntStream;
-import java.util.stream.Stream;
+import kong.unirest.json.JSONArray;
+import kong.unirest.json.JSONException;
+import kong.unirest.json.JSONObject;
+import org.apache.http.client.utils.URIBuilder;
 
 /**
- * Fetcher for ISBN using <a href="https://doi-to-bibtex-converter.herokuapp.com">https://doi-to-bibtex-converter.herokuapp.com</a>.
+ * Fetcher for ISBN using <a href="https://doi-to-bibtex-converter.herokuapp.com">doi-to-bibtex-converter.herokuapp</a>.
  */
 public class DoiToBibtexConverterComIsbnFetcher extends AbstractIsbnFetcher {
     private static final String BASE_URL = "https://doi-to-bibtex-converter.herokuapp.com";
@@ -85,23 +86,24 @@ private BibEntry jsonItemToBibEntry(JSONObject item) throws ParseException {
             entry.setField(StandardField.MONTH, getElementFromJSONArrayByKey(data, "month"));
             entry.setField(StandardField.DAY, getElementFromJSONArrayByKey(data, "day"));
             return entry;
-        } catch (JSONException exception) {
+        } catch (
+                JSONException exception) {
             throw new ParseException("CrossRef API JSON format has changed", exception);
         }
     }
 
     private String getElementFromJSONArrayByKey(JSONArray jsonArray, String key) {
         return IntStream.range(0, jsonArray.length())
-                .mapToObj(jsonArray::getJSONObject)
-                .map(obj -> obj.getString(key))
-                .findFirst()
-                .orElse("");
+                        .mapToObj(jsonArray::getJSONObject)
+                        .map(obj -> obj.getString(key))
+                        .findFirst()
+                        .orElse("");
     }
 
     private StandardEntryType evaluateBibEntryTypeFromString(String type) {
         return Stream.of(StandardEntryType.values())
-                .filter(entryType -> entryType.name().equalsIgnoreCase(type))
-                .findAny()
-                .orElse(StandardEntryType.Book);
+                     .filter(entryType -> entryType.name().equalsIgnoreCase(type))
+                     .findAny()
+                     .orElse(StandardEntryType.Book);
     }
 }
diff --git a/src/main/java/org/jabref/logic/importer/fetcher/isbntobibtex/IsbnFetcher.java b/src/main/java/org/jabref/logic/importer/fetcher/isbntobibtex/IsbnFetcher.java
index 02789d61b9d2..5de1b8086f43 100644
--- a/src/main/java/org/jabref/logic/importer/fetcher/isbntobibtex/IsbnFetcher.java
+++ b/src/main/java/org/jabref/logic/importer/fetcher/isbntobibtex/IsbnFetcher.java
@@ -1,5 +1,11 @@
 package org.jabref.logic.importer.fetcher.isbntobibtex;
 
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Optional;
+import java.util.regex.Pattern;
+
 import org.jabref.logic.help.HelpFile;
 import org.jabref.logic.importer.EntryBasedFetcher;
 import org.jabref.logic.importer.FetcherException;
@@ -10,15 +16,10 @@
 import org.jabref.model.entry.field.StandardField;
 import org.jabref.model.strings.StringUtil;
 import org.jabref.model.util.OptionalUtil;
+
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-import java.util.Optional;
-import java.util.regex.Pattern;
-
 /**
  * Fetcher to generate the Bibtex entry from an ISBN.
  * The default fetcher is the {@link OpenLibraryIsbnFetcher}.
@@ -60,7 +61,8 @@ public Optional<BibEntry> performSearchById(String identifier) throws FetcherExc
         try {
             identifier = removeNewlinesAndSpacesFromIdentifier(identifier);
             bibEntry = openLibraryIsbnFetcher.performSearchById(identifier);
-        } catch (FetcherException ex) {
+        } catch (
+                FetcherException ex) {
             LOGGER.debug("Got a fetcher exception for IBSN search", ex);
         } finally {
             while (bibEntry.isEmpty() && retryIsbnFetcher.iterator().hasNext()) {
diff --git a/src/test/java/org/jabref/logic/importer/fetcher/isbntobibtex/DoiToBibtexConverterComIsbnFetcherTest.java b/src/test/java/org/jabref/logic/importer/fetcher/isbntobibtex/DoiToBibtexConverterComIsbnFetcherTest.java
index 583aba5a63fe..8a19766feaa7 100644
--- a/src/test/java/org/jabref/logic/importer/fetcher/isbntobibtex/DoiToBibtexConverterComIsbnFetcherTest.java
+++ b/src/test/java/org/jabref/logic/importer/fetcher/isbntobibtex/DoiToBibtexConverterComIsbnFetcherTest.java
@@ -1,10 +1,7 @@
 package org.jabref.logic.importer.fetcher.isbntobibtex;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertThrows;
-import static org.mockito.Mockito.mock;
+import java.util.Optional;
 
-import org.apache.commons.lang3.NotImplementedException;
 import org.jabref.logic.importer.FetcherClientException;
 import org.jabref.logic.importer.FetcherException;
 import org.jabref.logic.importer.ImportFormatPreferences;
@@ -12,12 +9,15 @@
 import org.jabref.model.entry.BibEntry;
 import org.jabref.model.entry.field.StandardField;
 import org.jabref.model.entry.types.StandardEntryType;
+
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 import org.mockito.Answers;
 
-import java.util.Optional;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.mockito.Mockito.mock;
 
 public class DoiToBibtexConverterComIsbnFetcherTest extends AbstractIsbnFetcherTest {