jlink --genbom option creates a file named "bom" under the image output directory.

$ cat bom

#Thu Jan 28 08:59:41 PST 2016
#Please DO NOT Modify this file
command = --output baseimage --addmods java.base --genbom --modulepath jmods

The content is not BOM but instead the jlink options that create this image. This should be revisited.