DGS-4419: Adding validation error report in json serialization

[jshahc]

When a ValidationException is thrown during schema validation no information is giving regarding the specific validation errors encountered. The ValidationException toJSON() method is used on this class to print a report of the errors found. The stack trace would look like:

Caused by: org.apache.kafka.common.errors.SerializationException: Validation error in JSON io.confluent.kafka.serializers.json.KafkaJsonSchemaSerializerTest$User@637c6a91, Error report:
{
  "schemaLocation": "#/properties/firstName",
  "pointerToViolation": "#/firstName",
  "causingExceptions": [
    {
      "schemaLocation": "#/properties/firstName/oneOf/0",
      "pointerToViolation": "#/firstName",
      "causingExceptions": [],
      "keyword": "type",
      "message": "expected: null, found: String"
    },
    {
      "schemaLocation": "#/properties/firstName/oneOf/1",
      "pointerToViolation": "#/firstName",
      "causingExceptions": [],
      "keyword": "maxLength",
      "message": "expected maxLength: 2, actual: 4"
    }
  ],
  "keyword": "oneOf",
  "message": "#: 0 subschemas matched instead of one"
}

Made a new function validateJson to avoid cyclomatic complexity issues.

[jshahc]

Will this error report be sent back to customer via HTTP or will it be logged in SR logs for debugging? For security reasons we aren't supposed to log customer data in our logs

@sanjay-awatramani, I think the error report would show up on the connector's logs. In the above example stack trace, the report shows the field name but it isn't printing the actual value but just says length is greater than expected. But in other cases the actual value of the field might show up. For eg:

1. "message": "string [john] does not match pattern J."
2. "message": "-1 is not greater or equal to 0"

The second message shows up without the proposed change also. We aren't printing the complete message but just the field's name and where the validation is failing.

[sanjay-awatramani]

I think the error report would show up on the connector's logs. In the above example stack trace, the report shows the field name but it isn't printing the actual value but just says length is greater than expected. But in other cases the actual value of the field might show up. For eg:

1. "message": "string [john] does not match pattern J."
2. "message": "-1 is not greater or equal to 0"

The second message shows up without the proposed change also. We aren't printing the complete message but just the field's name and where the validation is failing.

@ap00rv , would this be a security violation?