Felicity_I.js

// assuming we are already defining Hapi server routes
const payloadSchema = Joi.object().keys({
    id           : Joi.string().guid().required(),
    name         : Joi.string().min(3).required(),
    callRequested: Joi.boolean().optional(),
    phoneNumber  : Joi.when(‘callRequested’, {
        is       : true,
        then     : Joi.string().min(10).required(),
        otherwise: Joi.string().allow(null).optional()
    })
});

server.route({
    method : 'POST',
    path   : '/document',
    handler: plugin.post,
    config : {
        validate: payloadSchema
    }
});