Hi,
the option is mentioned here: https://github.com/sequelize/sequelize/blob/master/docs/api/sequelize.md

Searching the repository it seems to be only mentioned in docs: https://github.com/sequelize/sequelize/search?utf8=%E2%9C%93&q=validateConnection

And when I tried to do this with latest sequelize, nothing seems to happen:

const poolConfig = {
    min: 1,
    max: maxConnections,
    idle: 60000,
    validateConnection: function (arg1) {
      console.log('validateConnection', this, arg1);
      return false;
    }
  };

Is this feature actually implemented?