Fix missing javadoc warnings (#4374)

Author: trask

buildSrc/src/main/kotlin/ai.java-conventions.gradle.kts

@@ -85,6 +85,20 @@ tasks {
     duplicatesStrategy = DuplicatesStrategy.FAIL
   }
 
+  named<Javadoc>("javadoc") {
+    with(options as StandardJavadocDocletOptions) {
+      source = "8"
+      encoding = "UTF-8"
+      docEncoding = "UTF-8"
+      charSet = "UTF-8"
+      breakIterator(true)
+
+      addStringOption("Xdoclint:none", "-quiet")
+      // non-standard option to fail on warnings, see https://bugs.openjdk.java.net/browse/JDK-8200363
+      addStringOption("Xwerror", "-quiet")
+    }
+  }
+
   withType<AbstractArchiveTask>().configureEach {
     isPreserveFileTimestamps = false
     isReproducibleFileOrder = true

buildSrc/src/main/kotlin/ai.smoke-test.gradle.kts

@@ -87,6 +87,21 @@ configurations.all {
 }
 
 tasks {
+  // FIXME (trask) copy-pasted from ai.java-conventions.gradle
+  named<Javadoc>("javadoc") {
+    with(options as StandardJavadocDocletOptions) {
+      source = "8"
+      encoding = "UTF-8"
+      docEncoding = "UTF-8"
+      charSet = "UTF-8"
+      breakIterator(true)
+
+      addStringOption("Xdoclint:none", "-quiet")
+      // non-standard option to fail on warnings, see https://bugs.openjdk.java.net/browse/JDK-8200363
+      addStringOption("Xwerror", "-quiet")
+    }
+  }
+
   register<Test>("smokeTest") {
     useJUnitPlatform()