netty: Don't use old-style classpath for shadow plugin

[ejona86]

Seems it was introduced unnecessarily in dc74a31. This also removes the
jcenter reference which is a repository that no longer receives updates.

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I noticed this when looking at upgrading the android plugin (because of the jcenter usage).

CC nastra

[ejona86]

CC @nastra

[nastra]

LGTM

[ejona86]

@Nestra, concerning your deleted comment, it seems shadow would work fine for our build with newer versions of Gradle because we depend on maven plugin. It seems this was the only incompatibility: johnrengelman/shadow#624

[nastra]

@Nestra, concerning your deleted comment, it seems shadow would work fine for our build with newer versions of Gradle because we depend on maven plugin. It seems this was the only incompatibility: johnrengelman/shadow#624

Ah that would make sense why the plugin worked. I ran into issues when upgrading to Gradle 7 with the shadow plugin in Apache Iceberg (apache/iceberg#2826, more specifically this line: https://github.com/apache/iceberg/pull/2826/files#diff-49a96e7eea8a94af862798a45174e6ac43eb4f8b4bd40759b5da63ba31ec3ef7R27), that's why I upgraded the plugin here as well.

I think we should probably still upgrade the shadow plugin from 6.1 to 7.0 in #8388 so that nobody runs into issues in the future in case the maven plugin is ever removed, wdyt?

[ejona86]

I think we should probably still upgrade the shadow plugin from 6.1 to 7.0 in #8388 so that nobody runs into issues in the future in case the maven plugin is ever removed, wdyt?

I agree.