isExistの実装を変更

source/src/main/java/one/nem/lacerta/source/file/FileManager.java

@@ -14,7 +14,7 @@ import java.util.List;
 public interface FileManager {
 
     File getFileRef();
-    boolean isExist();
+    boolean isExist(String name) throws IOException;
     boolean isDirectory();
     boolean isFile();
     boolean isWritable();

source/src/main/java/one/nem/lacerta/source/file/impl/FileManagerImpl.java

@@ -71,9 +71,9 @@ public class FileManagerImpl implements FileManager {
     }
 
     @Override
-    public boolean isExist() {
-        File file = this.path.toFile();
-        return file.exists();
+    public boolean isExist(String name) throws IOException {
+        Path resolvedPath = this.resolveStringPath(name);
+        return Files.exists(resolvedPath);
     }
 
     @Override