Upgrade Travis pipeline to OpenJDK11

[SudharakaP]

I've removed the jdk option of travis; this I believe is useless since it's only used when used in conjunction with language: java.

Also I've changed the linux distro to bionic since the default distro used by travis seems to be trusty and that doesn't have openjdk11 preinstalled (bionic does). This I believe makes the travis pipeline cleaner so that we don't have to manually install stuff on it and also could get rid of the jdk_switcher use oraclejdk8 part (which seems redundant anyways).

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[SudharakaP]

One of the things that came across my mind (through experience of my own) is that the migration of Travis to OpenJDK11 might impact the way the Google App Engine generator is handled currently. As far as I know in the standard mode of the app engine java11 is in beta and the deployment descriptor should be app.yaml rather than the current appengine-web.xml which will not work probably. I'll comment on this more when I do some more testing (we run a jhipster project on appengine so I'd have a better idea when trying to deploy it there), but if someone could chip in on this that would be wonderful 😄

[pascalgrimaud]

Thanks @SudharakaP

About the GAE, we have this ticket #9605
So for me, it's broken since at least 3 months...

[Tonterias]

I just tried to make it work with V6.2.0 and it is giving me the same error (even if I do the gcloud components install app-engine-java before)

D:\JHipster\testgae>gcloud components install app-engine-java

All components are up to date.

D:\JHipster\testgae>jhipster gae
INFO! Using JHipster version installed locally in current project's node_modules
INFO! Executing jhipster:gae
INFO! Options: from-cli: true
Welcome to Google App Engine Generator (Beta)
WARNING! This sub-generator is still in development, please report bugs on Github

Installing App Engine Java SDK
... Running: gcloud components install app-engine-java --quiet
events.js:174
throw er; // Unhandled 'error' event
^

Error: spawn gcloud ENOENT
at Process.ChildProcess._handle.onexit (internal/child_process.js:240:19)
at onErrorNT (internal/child_process.js:415:16)
at process._tickCallback (internal/process/next_tick.js:63:19)
Emitted 'error' event at:
at Process.ChildProcess._handle.onexit (internal/child_process.js:246:12)
at onErrorNT (internal/child_process.js:415:16)
at process._tickCallback (internal/process/next_tick.js:63:19)

No progress, sorry.

[SudharakaP]

@pascalgrimaud : I see, would you guys like me to give it a try to migrate the GAE deployment to Java 11 as well? That ticket seems to be worked by some people, so I don't know if progress has been made on that front. But by the looks of it the ticket seems to only address bugs in the current GAE generator which supports Java 8 only. I could try to write a new GAE generator for Java 11 with GAE standard. What I have in mind is to give users the option to choose between java 8 and 11 and then based on that generate the deployment files (app.yaml in the case of java 11 and keep the existing java 8 deployment files as it is).

[pascalgrimaud]

@SudharakaP : several points :

• gae : it's currently broken, so before trying to do something on this, we should try to fix it. See JHipster gae error #9605
• don't hesitate to open a specific issue (in the doubt) to discuss before submitting a PR
• we won't force you, you're just really really welcome if you want to contribute :) thank you so much

[SudharakaP]

@pascalgrimaud : Thanks for the suggestions. I've created a separate issue to discuss this (#10196).

[SudharakaP]

@pascalgrimaud : As per our discussion at #10216 (comment); I've changed this. Let me know if there's any issues 😄