I noticed that if I extend the JShell classpath using the --class-path
startup argument, I can import from packages in the JAR, but do not get
auto-completion for the import package names.

For example, using
jshell --class-path
~/.m2/repository/com/google/guava/guava/19.0/guava-19.0.jar

if I type
import com.<TAB>

I get
apple oracle sun

but I can type
import com.google.common.base.*

so, "google" is not an auto-complete option following "com."

Glad to report this elsewhere if you prefer.

Thanks in advance,
Patrick