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()
}