code: protected Boolean eval(final Object... _value)
      {
          final Boolean ret;
          if (_value == null) {
              ret = null;
          } else if (_value[0] instanceof String) {
              ret = Boolean.valueOf((String) _value[0]);
          } else if (_value[0] instanceof Boolean) {
              ret = (Boolean) _value[0];
          } else  {
              ret = false;
          }
          return ret;
      }
docs: Evaluates given <code>_value</code> and converts them to a
  {@link Boolean} value.
  
  @param _value    value to evaluate
  @return related evaluated boolean value