This finding comes from a usability study.

Users were asked to install Java in order to run a WebStart application. After the kernel installation, the application didn't start and users attempted to run the application again and were prompted (for the second time) to download Java again.
A few more details about the task:

Users were asked to run a WebStart application without Java installed on their machine. On the page, there was a detection that Java was not installed and users were prompted to install it.

After the kernel installation, the application didn't start running so users attempted to run the application again and were prompted (for the second time) to download Java.

Saying that, it looks like the detection didn't detect Java was already installed.