Excelsior JET is a certified Java SE implementation. Due to license restrictions, certified implementation should contain all Java SE APIs including reflection API. Compiler cannot prove that your application never uses reflection API, as in Java a new class can be dynamically loaded at any time and it can use reflection API. So the class and method names should be preserved in the compiled application. Note that parameter names are not included in reflection information and not preserved.
To avoid appearing of class and method names in the executables, Excelsior JET has an option to encrypt such strings. It can be enabled in JET Control Panel on the page TARGET in "EXECUTABLE SETTINGS" panel.
For more information see JET User's Guide, chapter "Intellectual property protection", section "Data protection"