I made a couple of experiments.
I tried Xwiki 13.7. - direct download of war - no success.
When I tried to build my own war from 13.7. - deployment in Weblogic was “successfull” (weblogic showed: Active). But in weblogic logs there were still these errors. But according to a comment they are not issue and can be ignored. When I ran it for the first time a configuration applet started loading, but it reached 92% and then it crashed. - In logs there were the same errors as here. But in my case I could not continue - it just crashed. When I put this war in Tomcat it worked with no problem, no errors.
Then I tried to build war from 13.8. But deployment on Weblogic did not succeed (UnsatisfiedDependencyException).
I tried to build war from 12.10.10 - deployment was ‘Active’, but it was not possibble to access the page - 404-NotFound and start configuration.
I tried to build war from 13.6. and 13.2 - the same behaviour as with 13.7.
So different versions with different results/behaviour on Weblogic. It seems Weblogic is not fully supported. Tomcat is supported, but when app runs on Tomcat it does not mean it can successfully run also on Weblogic. There are also some differences - e.g. when Tomcat processes headers it displays them in lowercase, Weblogic does not. Since it was not tested on Weblogic, one can not be sure it can successfully run. So that was the reason I first came up with a question, whether someone succeded in installing Xwiki on Weblogic.