All of the license-encumbered code lives in a separate directory, with a clear warning that it's licensed, and builds result in license-encumbered code being an entirely separate artifact from the purely Apache 2 licensed code. Besides that, anything that goes into package managers is also fully clean Apache 2 licensed code.
Literally the only way to "mix this up" is to not read anything, ignore package managers and build from source, then somehow decide to use 'x-pack' over 'elasticsearch'.
Releasing a software with license-encumbered code, using specialized marketing to vote down a comment critical to company's product, justifying the lawsuit for copyright infringement similar to Oracle. I think users can see through it.
Let's wait for the results of this case it will make it clear that if someone wants to use ELK, they should purchase a license or use Amazon version (as they will fight the case, a small startup can't have budget to even defend).
For a small development firm its better they use really open source product like Solr, Vespa or Lucene directly with OpenJDK, not the oracle JDK. Looking at this can only say Richard Stallman is a visionary and saw this when he defined Free Software and accompanying licenses.
Literally the only way to "mix this up" is to not read anything, ignore package managers and build from source, then somehow decide to use 'x-pack' over 'elasticsearch'.