Apache Ignite: ignite-core dependecies

[Dmitriy Pavlov]

Hi,

Why ignite-core depends to org.gridgain:ignite-shmem:1.0.0 ? Is it ok for
Apache projects to be dependent on proprietary software?

As I can see license is Apache 2.0, but where can I find sources?

Sincerely,
Dmitriy Pavlov