/{runtime}/events: Include eth_tx_hash in response

[ptrus]

Closes: #363

[mitjat]

Thank you! Have you tested the JSON response for an event with a corresponding tx, and for an event with no tx? (Events with no tx include one of deposit/withdrawal, IIRC. You can find them with make psql, then select ... from chain.runtime_events where "type"=...)

I can't wait for #410 to land so we get these tests/comparisons mostly automatically :)

[mitjat]

I believe this is not needed and has a slightly different meaning: That the value might be an explicit null (as opposed to being omitted, which is what we're doing). It's not 100% clear to me from the docs though.

Anyway, what we've been doing elsewhere (except tx_hash apparently ... that surprises me) was to just omit the field from required (line 1897), which is the standard openapi way of saying that this is an optional field.

[ptrus]

You are right, after testing it works as you expected. Updated as you suggested.

Not sure why it's like that for tx_hash, I guess it was preferred to return explicitly tx_hash=null field for events not tied to a transaction. I kept that as is in this PR, and can be updated in a separate PR.

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Note there is now some inconsistency, where eth_tx_hash will either be present or not (depending on if it originates from an ETH transaction), while the tx_hash will always be present, and explicitly null for block events. Can be updated in a follow-up PR.

[ptrus]

Have you tested the JSON response for an event with a corresponding tx, and for an event with no tx?

Tested now (after addressing review comments) and it works as expected in all cases (runtime event, evm runtime event, block event). There is a minor inconsistency between tx_hash and eth_tx_hash, see the other comment.