First of all, we apologize for the delay taken in our response.
javadoc is missing in that stack because it is a component of JDK. We are not allowed, for licensing purposes, to redistribute that. We only ship JRE-dist (which can be distributed). I am afraid that the only way of having it is via modifying the stack and installing a JDK in your machine as you initially said.
Let us know if we can help you with anything else.