Cannot set context at app level after v1.9.0

Cannot set context at app level anymore after v1.9.0. This is because a Tree child is automatically created under the app and context cannot be set after children have been added.

Comes from #4194 (3cca03d).

Reproduction Steps

const app = new cdk.App();
app.node.setContext('stage', 'dev');

Error Log

Error: Cannot set context after children have been added: Tree

Environment

• CLI Version : > 1.9.0
• Framework Version: > 1.9.0
• OS : all
• Language : all

Other

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This is 🐛 Bug Report

[eladb]

You can specify the context when you initialise the app:

new App({ context: { key: 'value' });

Closing for now.

[alex-a-ncino]

@eladb In the case of setting context when we initialize the app, how should the nested structures be handled? Context is expecting [key: string]: string which doesn’t allow setting a key to a nested object. Trying to set the context for js unit test.