Build: Use javadocJar helper to specify artifact explicitly

Creating javadocJar task for every project produces lots of unnecessary
tasks, some project don't even have code. Jar task without outDir
property set fails idea import with gradle 5.0+

libraries/kotlin.test/annotations-common/build.gradle

@@ -27,5 +27,6 @@ task sourcesJar(type: Jar, dependsOn: classes) {
 
 artifacts {
     archives sourcesJar
-    archives javadocJar
-}
+}
+
+javadocJar()

libraries/kotlin.test/common/build.gradle

@@ -29,9 +29,10 @@ classes.dependsOn.remove("compileJava")
 
 artifacts {
     archives sourcesJar
-    archives javadocJar
 }
 
+javadocJar()
+
 compileKotlinCommon {
     kotlinOptions {
         freeCompilerArgs = [

libraries/kotlin.test/js/build.gradle

@@ -44,9 +44,10 @@ task sourcesJar(type: Jar, dependsOn: classes) {
 
 artifacts {
     archives sourcesJar
-    archives javadocJar
 }
 
+javadocJar()
+
 task distJs(type: Copy) {
     dependsOn(compileKotlin2Js)
     from(compileKotlin2Js.kotlinOptions.outputFile)

libraries/kotlin.test/junit/build.gradle

@@ -24,9 +24,10 @@ jar {
 
 artifacts {
     archives sourcesJar
-    archives javadocJar
 }
 
+javadocJar()
+
 dist {
     from (jar, sourcesJar)
 }

libraries/kotlin.test/junit5/build.gradle

@@ -24,9 +24,10 @@ jar {
 
 artifacts {
     archives sourcesJar
-    archives javadocJar
 }
 
+javadocJar()
+
 dist {
     from (jar, sourcesJar)
 }

libraries/kotlin.test/jvm/build.gradle

@@ -47,10 +47,11 @@ task modularJar(type: Jar) {
 
 artifacts {
     archives sourcesJar
-    archives javadocJar
     archives modularJar
 }
 
+javadocJar()
+
 dist {
     from (jar, sourcesJar)
 }

libraries/kotlin.test/testng/build.gradle

@@ -21,9 +21,10 @@ jar {
 
 artifacts {
     archives sourcesJar
-    archives javadocJar
 }
 
+javadocJar()
+
 dist {
     from (jar, sourcesJar)
 }