@Nullable
    @Override public Boolean parse(String str) {
      if ("true".equalsIgnoreCase(str)) {
        return true;
      }
      if ("false".equalsIgnoreCase(str)) {
        return false;
      }
      return null;
    }
Reads a value according to this type.
@param in a data input
@return an instance of a value for the type or null
standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/properties/PropertyType.java