java_library fails with "Empty source path" on please 17.1.0

[hnridder]

(Maybe this belongs to the please-build/java-rules repo, but since this is a regression I'm reporting it here.)

I recently upgraded from 16.27.5 to 17.1.0, applied the java plugin and now java_library fails with an "Empty source path" error. Simple reproduction scenario: . plz init . plz init plugin java . Add the path to the local java binaries to build.path in .plzconfig . Create a small java file Main.java . Create a BUILD file:

java_library(
   name = 'core',
   srcs = ['Main.java'],
)

. plz build gives the output:

Build stopped after 180ms. 1 target failed:
    //:all
plz-out/gen/java/build_defs/java.build_defs:80:16: error: Empty source path

        return build_rule(
(... and more...)

Turning on debugging output reveals the origin to be targets.go:261, which is addMaybeNamedOrString(s, "tools",... So apparently the compiler isn't found by java.build_defs. I tried (among other things) setting [Plugin "java"].JavacTool to the fullpath of the java compiler, but that didn't help. Neither did fumbling around with the Toolchain setting.

Expected result:

• Local java installation is picked up.
• Documentation of the Java options (JavacTool, Toolchain) clarify how to use them.

[stale[bot]]

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