Add code action: Generate Delegate Methods...

[testforstephen]

Signed-off-by: Jinbo Wang [email protected]

Close #1042

[snjeza]

test this please

[fbricon]

Works pretty well, but like in Eclipse, we should be able to select delegate methods from different sources, so instead of selecting one delegate, we should have a multiple selection instead in the 1st step, and eventually be able to cherry pick which methods from any/all delegate to implement.

[fbricon]

Please allow selection of multiple delegates

[testforstephen]

I have tried to allow multiple selection at 1st step, but i didn't find a good way to handle the method name conflicts at 2st step.

For example, if you select two fields with the same class type at 1st, then select all at 2st step, eclipse adds some validation at the dialog, and disable the Generate button with error message "x duplicated methods selected". In VS Code UI, i didn't think of a good way to provide validation error in real time yet.

Keep it as single selection at 1st step, that could avoid the method conflict. Actually this is also the Intellij IDEA behavior.

[testforstephen]

test this please

[fbricon]

Ok fair enough. I can live with that for a bit.
I'm a bit annoyed by the message you receive when there's no more methods to delegate. Take this for instance:

private Runnable runner;

public void run() {
    runner.run();
}

It says No delegatable fields found in current class., which is incorrect. When there's no methods left to delegate, the message should something like All delegatable methods are already implemented. (or something better)

[testforstephen]

already updated the client side PR for the error message.

[testforstephen]

test this please