code: @Override
      public Object run(Map<String, Object> variables) {
          if (variables == null) {
              variables = new HashMap<String, Object>();
          }
          VariableResolverFactory factory = new MapVariableResolverFactory(variables, _propertyResolverFactory);
          return isCompiled() ? MVEL.executeExpression(_compiled, factory) : MVEL.eval(_expression, factory);
      }
docs: {@inheritDoc}