title: Data validation in AVRO
body: <p>I am new to AVRO and please excuse me if it is a simple question.
  I have a use case where I am using AVRO schema for record calls.</p>
  
  <p>Let's say I have avro schema </p>
  
  <pre><code>{
      "name": "abc",
      "namepsace": "xyz",
      "type": "record",
      "fields": [
          {"name": "CustId", "type":"string"},
          {"name": "SessionId", "type":"string"},
       ]
  }
  </code></pre>
  
  <p>Now if the input is like</p>
  
  <pre><code>{
      "CustId" : "abc1234"
      "sessionID" : "000-0000-00000"
  }
  </code></pre>
  
  <p>I want to use some regex validations for these fields and I want take this input only if it comes in particular format shown as above. Is there any way to specify in avro schema to include regex expression?</p>
  
  <p>Any other data serialization formats which supports something like this?</p>