code: static boolean valueAsBoolean(Map<String, Object> map, Key key, boolean defaultValue) {
          return Boolean.parseBoolean(valueAsString(map, key, String.valueOf(defaultValue)));
      }
docs: Fetches a value specified by key
  
  @param map XPP3 map equivalent
  @param key navigation key
  @param defaultValue Default value if no such key exists
  @return Boolean representation of the value