With JDK 8, you are unable to get Javadoc unless your tool meets the standards of doclint. Some of its rules are:

no self-closed HTML tags, such as <br /> or <a id="x" />
no unclosed HTML tags, such as <ul> without matching </ul>
no invalid HTML end tags, such as </br>
no invalid HTML attributes, based on doclint's interpretation of W3C HTML 4.01
no duplicate HTML id attribute
no empty HTML href attribute
no incorrectly nested headers, such as class documentation must have <h3>, not <h4>
no invalid HTML tags, such as List<String> (where you forgot to escape using &lt;)
no broken @link references
no broken @param references, they must match the actual parameter name
no broken @throws references, the first word must be a class name
Note that these are errors, not warnings. Break the rules and you get no Javadoc output.


Result are xxxx warnings like: warning: no description for @throws



add this in build.gradle: 


  if (JavaVersion.current().isJava8Compatible()) {
    allprojects {
      tasks.withType(Javadoc) {
        options.addStringOption('Xdoclint:none', '-quiet')