@Override
          public PopupStep<?> onChosen(LibraryOrderEntry libraryOrderEntry, boolean finalChoice) {
            if (libraryOrderEntry != null) {
              appendSources(libraryOrderEntry.getLibrary(), files);
            }
            else {
              for (Library libOrderEntry : librariesToAppendSourcesTo.keySet()) {
                if (libOrderEntry != null) {
                  appendSources(libOrderEntry, files);
                }
              }
            }
            return FINAL_CHOICE;
          }
@Override
          public PopupStep<?> onChosen(LibraryOrderEntry libraryOrderEntry, boolean finalChoice)