docs: public static File[] getUserExtensionVersionFiles(File installDir) {
  
          File[] versionFiles = null;
          String userDirLoc = System.getenv(BootstrapConstants.ENV_WLP_USER_DIR);
          File userDir = (userDirLoc != null) ? new File(userDirLoc) : ((installDir != null) ? new File(installDir, "usr") : null);
  
          if (userDir != null && userDir.exists()) {
              File userExtVersionDir = new File(userDir, "extension/lib/versions");
              if (userExtVersionDir.exists()) {
                  versionFiles = userExtVersionDir.listFiles(versionFileFilter);
              }
          }
  
          return versionFiles;
      }