Upgrades the javac version to 1.8

[nkibler]

Context: I'm about submit a PR for review that adds some utilities around the libraries.json file that contains metadata on Cloud API libraries. It'd be nice to use some Java 8 features in it (namely Streams).

[codecov]

Codecov Report

Merging #474 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #474   +/-   ##
=======================================
  Coverage   67.05%   67.05%           
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  Files          75       75           
  Lines        1988     1988           
  Branches      324      324           
=======================================
  Hits         1333     1333           
  Misses        513      513           
  Partials      142      142

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[loosebazooka]

This isn't a terrible idea. Gradle 5.0 wont run on java 7. Appengine java 8 is GA.

[elharo]

This needs to proceed with caution. Eclipse may be building with 1.7 still.

[elharo]

This would definitely break CT4E.

[nkibler]

I'll move my code to the IntelliJ plugin, then, since it sounds like Eclipse has its own implementation and won't benefit from it. Meanwhile, I'll leave this PR open because we'll want to upgrade the source eventually anyway. You can merge this in when CT4E migrates to Java 8.

[briandealwis]

This won't break Eclipse per se, but we're supporting Eclipse Mars (4.5) which still runs on Java 7. I wonder if we have any stats of the JVM versions being used for CT4E…

[nkibler]

I guess I could change this to target 7, but with an 8 source. It should allow for 8 features like Streams, but will likely disallow features that don't have a 7 bytecode analog (like default methods in interfaces). WDYT?

[etanshaul]

on second thought isn't that disallowed by the java compiler (source 8 with target 7)?

[loosebazooka]

I think we should at least check if we need to keep supporting mars, given that Eclipse has already released Neon+Oxygen and is on Photon.

Would rather not be involved in java version compiler shenanigans.

[elharo]

There are a lot of old Eclipse versions out in the wild. For comparison, we get GPE bug reports going back at least as far as 4.2. At some point, we will drop Mars support; but I don't want to do that until it buys us something really significant.

[nkibler]

I'll leave this up to you to do in the future then.

[loosebazooka]

@elharo @chanseokoh @briandealwis can we get some timeline on this?

[elharo]

There's no rush to do this. We can revisit when there's a compelling use case for Java 8 or dropping Eclipse Mars.