sbt.inc.Doc$JavadocGenerationFailed bumping sbt to 1.4.0+

[ignasi35]

See https://travis-ci.com/github/lagom/lagom/jobs/498873420#L772-L803

I've been doing some research and can't find any issue on existing repos about the error and potential workaround or solution. the only think I found was this failure report from play: playframework/playframework#10111

I've noticed this error is not sbt 1.5.0 related. It appears as soon as I bump sbt from 1.3.13 to 1.4.0 in .

Originally posted by @ignasi35 in #3224 (comment)

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Edit: adding some more notes.

The reproducer (see comment below) runs on scala 2.12.13 but requires JDK11.

[ignasi35]

Unlike playframework/playframework#10111, this is repeatable.

[ignasi35]

The easiest reproducer is:

1.clone master
2. set 1.4.0 on project/build-properties
3. run sbt Javaunidoc/doc

[ignasi35]

May be related to lightbend/genjavadoc#264 and lightbend/genjavadoc#220

[ignasi35]

The workaround in the case of Lagom is to use JDK8 when bumping to sbt 1.4.0.

Here's a summary:

• JDK 11 + sbt 1.3.13: PASSED
• JDK 11 + sbt 1.4.0: FAILED
• JDK 8 + sbt 1.x.y: PASSED

[ignasi35]

More likely related to lightbend/cloudflow@19bad77#diff-cb9f468b80bb3e0f757971d036ce90c5885fb3a406cdb76ff63a808a74f70332R16 since the error seems related to the JDK and not the scala version.