Graal is EPL, GPLv2, LGPL licensed.
Now Android has Google's own J++, limiting what kind of Java libraries are portable to the platform.
At the same time, some OEMs are adopting Android instead of Embedded Java, thus increasing the fragmentation about what Java libraries are actually portable.
Google just though they could let Sun close doors and get away with how they created their own J++.
Having said that, Graal and its related projects are all open source, with a license listing available in its README: