private static void throwUnchecked(Throwable throwable) {
    if (throwable instanceof RuntimeException) {
      throw (RuntimeException) throwable;
    }
    if (throwable instanceof Error) {
      throw (Error) throwable;
    }
  }
A bridge class for operating on log4j, such as changing log level, etc.
<p/>
Will call the methods in {@link InternalLog4jUtils} to actually operate on the log4j stuff.
hbase-logging/src/main/java/org/apache/hadoop/hbase/logging/Log4jUtils.java