APM Page doesn't display when i18n.locale: ja-JP

[kindsun]

Kibana version:

7.9.0

Steps to reproduce:

1. Set i18n.locale: ja-JP in kibana.yml
2. Load APM

Screenshots (if relevant):

Notes

• This seemed to work as expected on master so may have been fixed? Is the fix backportable?
• When attempting to repro the issue locally, screen came up blank with no console error

[elasticmachine]

Pinging @elastic/apm-ui (Team:apm)

[sorenlouv]

Fourth issue regarding this: #72794, #67082, #72984
@smith Any ideas?

[sorenlouv]

This issue is exactly the same as #72984 #68037. where xpack.apm.kueryBar.placeholder was invalid.
I tried to lookup xpack.apm.kueryBar.placeholder in the Japanese translation file but didn't find it in either master or 7.9 which seems odd.

[smith]

@sqren the issue with the query bar was #68037.

xpack.apm.kueryBar.placeholder is not there on master, but the incorrect version (that was fixed in #68037) is still present on 7.9.0.

#68037 was backported to 7.8 and 7.x when it was created, so I'm not sure why it wouldn't be on 7.9. Is it a weird timing thing with how and when the branches are created?

@Bamieh could you please check this out?

[smith]

Created #76204 to backport to 7.9. I believe this will go out with 7.9.1 as long as it gets merged shortly.

[sorenlouv]

@smith @Bamieh I think I figured it out. git bisect to the rescue!

3rd of June
@smith adds commit 8423f24 (via #68145) to 7.x which contains the fix for xpack.apm.kueryBar.placeholder.

11th of July
@Bamieh adds commit 9b56184 (via #71388) to 7.x which reverts the fix for xpack.apm.kueryBar.placeholder

14th of August
@Bamieh adds commit 9b40b27 (via #74997) to 7.x which remove the line for xpack.apm.kueryBar.placeholder completely

Conclusion
I don't know what happened with #71388 (11th of July). I assume that was a mistake to revert the fix made in #68145 (3rd of June). The change made in #74997 (14th of August) makes sense since it removes an invalid translation. Unfortunately this didn't make it into the 7.9.0 release which was build 12th of August.
Thus we shipped a broken translation string with 7.9.0 which breaks APM for Japanese users. This will not be a problem in 7.9.1 since the broken string has already been removed (in #74997) and will be re-added correctly in #76204