CCDM: implement Flow.start() API

[manolo]

This fixes #6133

• Adding the FlowBootstrap.js file that is distributed in flow-client.jar. It is based in BootstrapHandler.js but with small modifications to be an ES module.
• Copying the flow-client file as FlowClient.js to be distributed in the client jar file. It needs to be wrapped in a function so as it can be lazily executed.
• Adding definition files for FlowBootstrap.js and FlowClient.js files so as they can be used from typescript.
• Implemented the Flow.start() method with the following steps
  • Send a XHR request to flow JavaScriptBoostrapHandler in order to get create session
    and get the application configuration
  • Load FlowBootstrap.js chunk and initialize it with the response from the previous step
  • Load FlowClient.js chunk and run it.
• Added tasks to maven and npm to correctly build the Flow client library and test it.

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This change is 

[platosha]

Reviewed 10 of 10 files at r1.
Reviewable status: 2 unresolved discussions, 0 of 1 LGTMs obtained (waiting on @manolo and @qtdzz)

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flow-client/src/main/resources/META-INF/resources/frontend/Flow.ts, line 60 at r1 (raw file):

    }

    async __initFlowClient(clientMod: any): Promise<void> {

How about using a private modifier from TypeScript instead of __memberName prefixes?

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flow-client/src/main/resources/META-INF/resources/frontend/Flow.ts, line 85 at r1 (raw file):

                    resolve(JSON.parse(httpRequest.responseText));
                } else {
                    reject(httpRequest);

Nit: typically a Promise rejection is expected to give an error object, same as with throw. Here we give a request instead.

Would be probably nicer to have some error object here. The caller method will carry this rejection outside, I think.

Not blocking for now, fine by me to improve this later.

[manolo]

@platosha had to remove FF because failed in TC

Reviewable status: 1 unresolved discussion, 0 of 1 LGTMs obtained (waiting on @platosha and @qtdzz)

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flow-client/src/main/resources/META-INF/resources/frontend/Flow.ts, line 60 at r1 (raw file):

Previously, platosha (Anton Platonov) wrote…

How about using a private modifier from TypeScript instead of __memberName prefixes?

Done.

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flow-client/src/main/resources/META-INF/resources/frontend/Flow.ts, line 85 at r1 (raw file):

Previously, platosha (Anton Platonov) wrote…

Nit: typically a Promise rejection is expected to give an error object, same as with throw. Here we give a request instead.

Would be probably nicer to have some error object here. The caller method will carry this rejection outside, I think.

Not blocking for now, fine by me to improve this later.

Done. Also added a test for this code.

[platosha]

Reviewed 4 of 4 files at r2.
Reviewable status: complete! all discussions resolved, 1 of 1 LGTMs obtained (waiting on @qtdzz)