Apply suggestions from code review

Co-authored-by: Sebastian Stenzel <overheadhunter@users.noreply.github.com>

Author: infeo

src/main/java/org/cryptomator/cryptofs/DirectoryIdLoader.java

@@ -8,7 +8,6 @@
 import java.nio.channels.Channels;
 import java.nio.channels.FileChannel;
 import java.nio.charset.StandardCharsets;
-import java.nio.file.Files;
 import java.nio.file.NoSuchFileException;
 import java.nio.file.Path;
 import java.nio.file.StandardOpenOption;
@@ -25,7 +24,6 @@ public DirectoryIdLoader() {
 
 	@Override
 	public String load(Path dirFilePath) throws IOException {
-		//TODO: replace by Files.readString(StandardCharsets.UTF_8)
 		try (FileChannel ch = FileChannel.open(dirFilePath, StandardOpenOption.READ);
 			 InputStream in = Channels.newInputStream(ch)) {
 			long size = ch.size();

src/test/java/org/cryptomator/cryptofs/DeleteNonEmptyCiphertextDirectoryIntegrationTest.java

@@ -16,6 +16,7 @@
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 import org.mockito.Mockito;
@@ -28,6 +29,7 @@
 import java.nio.file.FileSystem;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.function.Predicate;
 import java.util.stream.Stream;
 
 import static java.nio.file.StandardOpenOption.CREATE_NEW;
@@ -159,21 +161,35 @@ private Path firstEmptyCiphertextDirectory() throws IOException {
 		try (Stream<Path> allFilesInVaultDir = Files.walk(pathToVault)) {
 			return allFilesInVaultDir //
 					.filter(Files::isDirectory) //
-					.filter(this::isEmptyDirectory) //
+					.filter(this::isEmptyCryptoFsDirectory) //
 					.filter(this::isEncryptedDirectory) //
 					.findFirst() //
 					.get();
 		}
 	}
 
-	private boolean isEmptyDirectory(Path path) {
+	private boolean isEmptyCryptoFsDirectory(Path path) {
+		Predicate<Path> isIgnoredFile = p -> Constants.DIR_ID_FILE.equals(p.getFileName().toString());
 		try (Stream<Path> files = Files.list(path)) {
-			return files.filter(p -> p.getFileName().toString().equals(Constants.DIR_ID_FILE)).count() == 0;
+			return files.noneMatch(isIgnoredFile.negate());
 		} catch (IOException e) {
 			throw new UncheckedIOException(e);
 		}
 	}
 
+	@Test
+	@DisplayName("Tests internal cryptofs directory emptiness definition")
+	public void testCryptoFsDirEmptiness() throws IOException {
+		var emptiness = pathToVault.getParent().resolve("emptiness");
+		var ignoredFile = emptiness.resolve(Constants.DIR_ID_FILE);
+		Files.createDirectory(emptiness);
+		Files.createFile(ignoredFile);
+
+		boolean result = isEmptyCryptoFsDirectory(emptiness);
+
+		Assertions.assertTrue(result, "Directory containing only dir id file is not considered empty");
+	}
+
 	private boolean isEncryptedDirectory(Path pathInVault) {
 		Path relativePath = pathToVault.relativize(pathInVault);
 		String relativePathAsString = relativePath.toString().replace(File.separatorChar, '/');