docs: public boolean optBoolean(String key, boolean defaultValue) {
          Object val = this.opt(key);
          if (NULL.equals(val)) {
              return defaultValue;
          }
          if (val instanceof Boolean){
              return ((Boolean) val).booleanValue();
          }
          try {
              // we'll use the get anyway because it does string conversion.
              return this.getBoolean(key);
          } catch (Exception e) {
              return defaultValue;
          }
      }