code: public static Level valueOf(final String name) {
          Objects.requireNonNull(name, "No level name given.");
          final String levelName = toUpperCase(name);
          final Level level = LEVELS.get(levelName);
          if (level != null) {
              return level;
          }
          throw new IllegalArgumentException("Unknown level constant [" + levelName + "].");
      }
docs: Return the Level associated with the name.
  
  @param name The name of the Level to return.
  @return The Level.
  @throws java.lang.NullPointerException if the Level name is {@code null}.
  @throws java.lang.IllegalArgumentException if the Level name is not registered.