Ensure database is not null in explicit request

Author: injectives

driver/src/main/java/org/neo4j/driver/BookmarkSupplier.java

@@ -29,7 +29,7 @@ public interface BookmarkSupplier {
     /**
      * Supplies a set of bookmarks for a given database.
      *
-     * @param database the database name
+     * @param database the database name, must not be {@code null}
      * @return the set of bookmarks, must not be {@code null}
      */
     Set<Bookmark> getBookmarks(String database);

testkit-backend/src/main/java/neo4j/org/testkit/backend/messages/requests/TestkitBookmarkSupplier.java

@@ -18,10 +18,10 @@
  */
 package neo4j.org.testkit.backend.messages.requests;
 
+import java.util.Objects;
 import java.util.Set;
 import java.util.concurrent.CompletionStage;
 import java.util.function.BiFunction;
-import java.util.function.Supplier;
 import java.util.stream.Collectors;
 import lombok.RequiredArgsConstructor;
 import neo4j.org.testkit.backend.TestkitState;
@@ -37,20 +37,21 @@ class TestkitBookmarkSupplier implements BookmarkSupplier {
 
     @Override
     public Set<Bookmark> getBookmarks(String database) {
-        return getBookmarksFromTestkit(() -> database);
+        Objects.requireNonNull(database, "database may not be null");
+        return getBookmarksFromTestkit(database);
     }
 
     @Override
     public Set<Bookmark> getAllBookmarks() {
         return getBookmarksFromTestkit(null);
     }
 
-    private Set<Bookmark> getBookmarksFromTestkit(Supplier<String> databaseSupplier) {
+    private Set<Bookmark> getBookmarksFromTestkit(String database) {
         var callbackId = testkitState.newId();
         var bodyBuilder =
                 BookmarksSupplierRequest.BookmarksSupplierRequestBody.builder().id(callbackId);
-        if (databaseSupplier != null) {
-            bodyBuilder = bodyBuilder.database(databaseSupplier.get());
+        if (database != null) {
+            bodyBuilder = bodyBuilder.database(database);
         }
         var callback =
                 BookmarksSupplierRequest.builder().data(bodyBuilder.build()).build();