I think it is correct to say that in the “normal” or “supported” use of DevTest, there is no need for Oracle JDK in DevTest. Only JRE is needed and needs to be distributed.
Whenever, you use java statements in beanshell scripts then those statements are interpreted (late type binding) by beanshell they are not compiled through JDK and then executed.
Obviously, within your company as a practice you could decide to limit the lines of actual scripting inside a .vsm or .tst file and instead provide that functionality compiled and stored in a jar file. E.g. in Eclipse it might be easier to code and debug those lines of java. In that case you are developing and compiling some java outside of DevTest. Your custom jar file is then added to the HotDeploy directory or lib/shared directory or can be distributed but it is already compiled so still no JDK needed anymore.
Cheers,
Danny