Jarsigner is designed to be used by Java. And both Jarsigner, and the Java command used to actually run the code on Oracle Java and OpenJDK use the same code –

Jarsigner is designed to be used by Java. And both Jarsigner, and the Java command used to actually run the code on Oracle Java and OpenJDK use the same code – so they both only see the zip entries. This issue only exists because Android reused a signing process designed for an entirely different execution environment.