Fix checkstyle

Signed-off-by: tvallin <[email protected]>

Author: tvallin

common/common/src/main/java/io/helidon/build/common/FileUtils.java

@@ -26,6 +26,7 @@
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.URL;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.FileSystem;
 import java.nio.file.FileSystemAlreadyExistsException;
 import java.nio.file.FileSystems;
@@ -1149,9 +1150,11 @@ public static URL urlOf(Path path) {
      * @return {@code true} if the file is a submodule, {@code false} otherwise
      */
     public static boolean isSubModule(Path path) {
-        try {
-            BufferedReader reader = new BufferedReader(new FileReader(path.toFile()));
-            return reader.readLine().startsWith("[submodule");
+        try (BufferedReader reader = new BufferedReader(new FileReader(path.toFile(), StandardCharsets.UTF_8))) {
+            String line = reader.readLine();
+            return line == null
+                    ? false
+                    : line.startsWith("[submodule");
         } catch (IOException e) {
             throw new UncheckedIOException(e);
         }