title: How to conditionally invoke spring validators
body: <p>I have a model like below. Existing code already has validations on individual properties. Now I have a requirement to ignore existing validations on billing_country and address if <code>buyer.method</code> is <code>foo</code>. I was thinking I could have a custom validator at <code>buyer</code> level, check for method and invoke validations only when <code>buyer.method!=foo</code>. Is this a valid approach? Are there any better alternatives?</p>
  
  <pre><code>"buyer": {
      "method": "foo",
      "instruments": [
        {
          "card": {
            "type": "MASTERCARD",
            "number": "234234234234234",
            "expire_month": "12",
            "expire_year": "2017",
            "billing_country" : "US"
            "Address" : {
               "line1": "summer st",
               "city": "Boston"
               "country": "US"
             }
          }
        }
      ]
  }
  </code></pre>