cdk-10to12
Hack all node10 Lambdas to use node12.
Note that this is definitely not safe in general. But you may well find that your code runs fine in node12.
import { cdk10to12 } from 'cdk-10to12';
...
const app = new cdk.App();
// Then attach things to app, like stacks, with constructs and Lambda functions
// Then force all uses of node10 Lambda runtimes to become node12, and
// hope that you don't get any bugs
cdk10to12(app);