How to provide generated data-binding classes in a Gradle Javadoc task?

Question

With this Gradle task I've used to extract AAR, in order to generate Javadoc:

task javadoc(type: Javadoc) {
    doFirst {
        configurations.implementation.filter { it.name.endsWith('.aar') }.each { aar ->
            copy {
                from zipTree(aar)
                include "**/classes.jar"
                into "$buildDir/tmp/aarsToJars/${aar.name.replace('.aar', '')}/"
            }
        }
    }
    failOnError false
    options.linkSource true
    options.links("https://docs.oracle.com/en/java/javase/11/docs/api/")
    options.links("https://developer.android.com/reference/")
    title = "Colorpicker Library ${versionName} API"
    source = android.sourceSets.main.java.srcDirs
    classpath = files(new File("${android.sdkDirectory}/platforms/${android.compileSdkVersion}/android.jar"))
    classpath += project.files(android.getBootClasspath().join(File.pathSeparator))
    classpath += fileTree(dir: "$buildDir/tmp/aarsToJars/")
    configurations.implementation.setCanBeResolved(true)
    classpath += configurations.implementation
    destinationDir = file("${project.buildDir}/outputs/javadoc/")
    exclude "**/BuildConfig.java"
    exclude "**/R.java"
}

It fails since I've enabled androidx.databinding 7.2.1 inside the library module:

> Task :library:javadoc
...\ColorPickerDialogFragment.java:24: error: package com.acme.databinding does not exist
import com.acme.databinding.DialogColorPickerBinding;
                                          ^
...\ColorPickerDialogFragment.java:46: error: cannot find symbol
    DialogColorPickerBinding mDataBinding;
    ^
  symbol:   class DialogColorPickerBinding
  location: class ColorPickerDialogFragment
2 errors

How can I add these generated sources to classpath ? Ignoring the class import doesn't seem to be an option. Or does javadoc have to depend on the task, which generates these (bad timing)? In general, exclude "**/ColorPickerDialogFragment.java" is not the answer I'm looking for.

Answer 1

Extracting the built AAR and putting it on classpath provides the generated classes -
but it's a whole lot more elegant to reference the intermediate classes.jar already:

task javadoc(type: Javadoc) {

    ...
    doFirst {

        ...
        def aar_main = new File("$buildDir/intermediates/aar_main_jar")
        if (aar_main.exists()) {
            copy {
                from aar_main
                include "**/classes.jar"
                into "$buildDir/tmp/aarsToJars/aar_main_jar/"
            }
        }
    }
}

One can also check .exists() before already:

javadoc.onlyIf {
    new File("$buildDir/intermediates/aar_main_jar").exists()
}