protected static void setInvalid() {
    if (JBoss6VFS.valid == Boolean.TRUE) {
      log.debug("JBoss 6 VFS API is not available in this environment.");
      JBoss6VFS.valid = Boolean.FALSE;
    }
  }
Mark this {@link VFS} as invalid for the current environment.
src/main/java/org/apache/ibatis/io/JBoss6VFS.java