code: public static synchronized void setLogFilter(LogFilter logFilter) {
          Preconditions.checkArgument(logFilter == null, "logFilter == null");
          Limb.log(LogLevel.DEBUG, "Set LogFilter to instance of class " + logFilter.getClass().getName() + '.');
          LOG_FILTER = logFilter;
      }
docs: Sets the current log filter.
  
  @param logFilter
  the new {@link LogFilter}, cannot be <code>null</code>.