[wilx]

Class-based incremental compilation assumes every Java source produces an inferred output file. A zero-byte compilation unit produces no class file, so it was detected as modified on every invocation.

This change records whether a source is empty using the file attributes already collected during source scanning. A modified zero-byte source is treated as ignorable only when its inferred output does not exist. If an output does exist, the source remains stale so truncating an existing source is still detected as a change.

A regression test compiles an empty source twice with class-based incremental detection and verifies that the second invocation reports all classes as up to date.

Fixes #1000.

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[wampiedriessen]

For this PullRequest, please also consider the case where a Java source file consists of only comments.
Making it effectively empty as well

[wilx]

This would require parsing the Java file. There are parsers that can be used, I think. However, it seems like overkill for already marginal situation.

[github-actions]

@desruisseaux Please assign appropriate label to PR according to the type of change.

[desruisseaux]

Thanks!