src/jdk.jpackage/share/classes/jdk/jpackage/internal/RelativeFileSet.java

*** 105,114 ****
          return files;
      }
  
      @Override
      public String toString() {
          return "RelativeFileSet {basedir:" + basedir
!                 + ", files: {" + files + ")}";
      }
  
  }
--- 105,117 ----
          return files;
      }
  
      @Override
      public String toString() {
+         if (files.size() ==  1) {
+             return "" + basedir + File.pathSeparator + files;
+         }
          return "RelativeFileSet {basedir:" + basedir
!                 + ", files: {" + files + "}";
      }
  
  }