[jnigen] Parameter names are lost

[stuartmorgan-g]

Per recommendation in recent discussion, I'm now generating code from flutter build apk output without referencing any source in my config YAML. The result is that a Java method like 'void seekTo(int location)becomesvoid seekTo(int i)`. Parameter names are very useful contextual documentation, so we need a recommended generation config that doesn't lose that information.

[HosseinYousefi]

Will be solved by https://github.com/dart-lang/native/issues/1079