code: public void setActivate(RuleProxyField ruleProxyField,
              RuleContext ruleContext)
      {
          if (ruleProxyField.isInActive()) // only do it if the field changes
          {
              m_activateFields.add(ruleProxyField.getProxyField());
              ruleContext.addActivate(ruleProxyField);
          }
      }
docs: /* (non-Javadoc)
  @see nz.co.senanque.rules.RuleSession#setActivate(nz.co.senanque.validationengine.ProxyField, nz.co.senanque.rules.RuleContext)