For #604. Add helpful comments

Author: binkley

build.gradle

@@ -105,7 +105,8 @@ java {
     toolchain {
         languageVersion.set(JavaLanguageVersion.of("$jdkVersion"))
     }
-    withJavadocJar()
+    withJavadocJar() // Javadoc for "main" source code
+    // More configuration needed for "test" or "integrationTest" source code
 }
 
 tasks.withType(JavaCompile) {

pom.xml

@@ -458,8 +458,9 @@
                         <id>javadoc-jars</id>
                         <phase>package</phase>
                         <goals>
-                            <goal>jar</goal>
-                            <goal>test-jar</goal>
+                            <goal>jar</goal> <!-- Javadoc for "main" source code -->
+                            <goal>test-jar</goal> <!-- Javadoc for "test" source code -->
+                            <!-- More configuration needed for "integrationTest" source code -->
                         </goals>
                     </execution>
                 </executions>