title: DynamoDB ProjectionExpression exclude attribute (all fields except one)
body: <p>I have a requirement where my dynamodb table has many attributes, and i need all of them in the projection expression except one or two columns which i dont need in response. (I am scanning the table).
  Is there a way how can i define this in ProjectionExpression (all except this one column).
  I have seen examples where ProjectionExpression only takes what all "is required" and not the other way.</p>