RFR JDK-8174248: partialUpdateFooMainClass test in tools/jar/modularJar/Basic.java needs to be re-examined

[Xueming Shen]

Hi,

Please review the test change for JDK-8174248

issue: https://bugs.openjdk.java.net/browse/JDK-8174248
webrev: http://cr.openjdk.java.net/~sherman/8174248/webrev

The change is to simply rename the entry name from "IAmNotTheEntryPoint"
to a "packaged" one as " jdk.test.foo.IAmNotTheEntryPoint" to satisfy the
newly added sanity check in j.l.m.ModuleDescriptor.Builder.mainClass(), in
which the "main-class in unnamed package" is no longer allowed (and the
named package must exist in module "packages") .

Arguably it might be desired for "jar" tool to also verify whether or not the
"main-class" really exists in the module jar file (the implementation does not
verify the existence of the main-class for the manifest  for now, the newly
added module related code follows the "convention"), but this probably should
be handled/discussed in a separate rfe.

Thanks,
Sherman