Add Kotlindoc-only publishing and enable for Dataconnect (#7330)

Adds a new field for firebase libraries to enable kotlindoc-only
publishing if they publish docs. This has been enabled for Dataconnect
as well. When this is enabled, no `android` folder is generated by
Dackka.

Author: emilypgoogle

firebase-dataconnect/firebase-dataconnect.gradle.kts

@@ -28,6 +28,7 @@ firebaseLibrary {
   libraryGroup = "dataconnect"
   testLab.enabled = false
   publishJavadoc = true
+  onlyPublishKotlindoc = true
   releaseNotes {
     name.set("{{data_connect_short}}")
     versionName.set("data-connect")

plugins/src/main/java/com/google/firebase/gradle/plugins/BaseFirebaseLibraryPlugin.kt

@@ -56,6 +56,7 @@ abstract class BaseFirebaseLibraryPlugin : Plugin<Project> {
       project.gradle.sharedServices.registerIfAbsent<GMavenService, _>("gmaven")
       previewMode.convention("")
       publishJavadoc.convention(true)
+      onlyPublishKotlindoc.convention(false)
       artifactId.convention(project.name)
       groupId.convention(project.provider { project.group.toString() })
       libraryGroup.convention(artifactId)

plugins/src/main/java/com/google/firebase/gradle/plugins/DackkaGenerationTask.kt

@@ -19,6 +19,7 @@ package com.google.firebase.gradle.plugins
 import java.io.File
 import javax.inject.Inject
 import org.gradle.api.DefaultTask
+import org.gradle.api.Project
 import org.gradle.api.file.FileCollection
 import org.gradle.api.file.RegularFileProperty
 import org.gradle.api.provider.ListProperty
@@ -120,7 +121,8 @@ constructor(private val workerExecutor: WorkerExecutor) : GenerateDocumentationT
         "java.lang.Override",
       )
     val annotationsNotToDisplayKotlin = listOf("kotlin.ExtensionFunctionType")
-
+    // A null path disables javadoc generation
+    val javadocPath: String? = "android".takeUnless { publishKotlindocOnly(project) }
     val jsonMap =
       mapOf(
         "moduleName" to "",
@@ -152,7 +154,7 @@ constructor(private val workerExecutor: WorkerExecutor) : GenerateDocumentationT
                 JSONObject(
                     mapOf(
                       "docRootPath" to "/docs/reference/",
-                      "javaDocsPath" to "android",
+                      "javaDocsPath" to javadocPath,
                       "kotlinDocsPath" to "kotlin",
                       "projectPath" to "client/${clientName.get()}",
                       "includedHeadTagsPathJava" to
@@ -171,6 +173,14 @@ constructor(private val workerExecutor: WorkerExecutor) : GenerateDocumentationT
     return JSONObject(jsonMap)
   }
 
+  /**
+   * Checks if the [Project] should only release Kotlindocs
+   *
+   * This is done via the [FirebaseLibraryExtension.onlyPublishKotlindoc] property.
+   */
+  private fun publishKotlindocOnly(project: Project) =
+    project.firebaseLibrary.onlyPublishKotlindoc.get()
+
   private fun createExternalLinks(
     packageLists: ListProperty<File>
   ): List<ExternalDocumentationLink> {

plugins/src/main/java/com/google/firebase/gradle/plugins/FirebaseLibraryExtension.kt

@@ -69,6 +69,22 @@ constructor(val project: Project, val type: LibraryType) {
    */
   abstract val publishJavadoc: Property<Boolean>
 
+  /**
+   * Only publish Kotlindocs instead of also publishing Javadocs for this library.
+   *
+   * This property is only effective when `publishJavadoc` is `true`.
+   *
+   * Defaults to `false`.
+   *
+   * ```sh
+   * ./gradlew :firebase-common:kotlindoc
+   * ```
+   *
+   * @see [FirebaseLibraryExtension]
+   * @see publishJavadoc
+   */
+  abstract val onlyPublishKotlindoc: Property<Boolean>
+
   /**
    * Indicates the library is in a preview mode (such as `alpha` or `beta`).
    *