javadoc rule doc_deps should (have an be option to be) more lenient and ignore any missing '_JavadocInfo'

[vorburger]

I wouldl like https://docs.enola.dev/dev/javadoc/ not to include the JavaDoc of ProtoBuf, gRPC and javax.annotation, but only of that project itself - seems reasonable, no? 😆

But when I change this:

javadoc(
    name = "javadoc",
    doc_url = "https://docs.enola.dev/dev/javadoc/",
    deps = [
        ":enola",
        "@enola_maven//:com_google_protobuf_protobuf_java",
        "@enola_maven//:com_google_protobuf_protobuf_java_util",
        "@enola_maven//:javax_annotation_javax_annotation_api",
    ],
)

to this:

javadoc(
    name = "javadoc",
    doc_url = "https://docs.enola.dev/dev/javadoc/",
    deps = [
        ":enola",
    ],
    doc_deps = [
        "@enola_maven//:com_google_protobuf_protobuf_java",
        "@enola_maven//:com_google_protobuf_protobuf_java_util",
        "@enola_maven//:javax_annotation_javax_annotation_api",
    ],
)

then bazelisk build //java/dev/enola:javadoc just fails like this:

ERROR: /home/vorburger/git/github.com/enola-dev/enola/java/dev/enola/BUILD:77:8: in doc_deps attribute of javadoc rule //java/dev/enola:javadoc: '@@protobuf+//java/core:core' does not have mandatory providers: '_JavadocInfo'
ERROR: /home/vorburger/git/github.com/enola-dev/enola/java/dev/enola/BUILD:77:8: in doc_deps attribute of javadoc rule //java/dev/enola:javadoc: '@@protobuf+//java/util:util' does not have mandatory providers: '_JavadocInfo'
ERROR: /home/vorburger/git/github.com/enola-dev/enola/java/dev/enola/BUILD:77:8: in doc_deps attribute of javadoc rule //java/dev/enola:javadoc: '@@rules_jvm_external++maven+enola_maven//:javax_annotation_javax_annotation_api' does not have mandatory providers: '_JavadocInfo'
ERROR: /home/vorburger/git/github.com/enola-dev/enola/java/dev/enola/BUILD:77:8: Analysis of target '//java/dev/enola:javadoc' failed
ERROR: Analysis of target '//java/dev/enola:javadoc' failed; build aborted
INFO: Elapsed time: 0.425s, Critical Path: 0.00s
INFO: 1 process: 1 internal.
ERROR: Build did NOT complete successfully

This seems unncessarily strict, no? In a real world project, one may well depends on targets which do not correctly publish JavaDoc themselves. It should (IMHO) still be possible to generate JavaDoc for a project with such dependencies - and simply have the rules_jvm_external javadoc rule ignore a few missing implicit javadoc targets.