File: t.h

typedef union {
   int i;
   char c;
} Foo;

typedef Foo Bar;

void func(Bar* b);

----

$ jextract -d . t.h

only t.class (Header class) and t$Bar.class (Struct class) are generated. But t.class has type reference to non-existent t$Foo

$ javap t

public interface t {
  public abstract void func(java.foreign.memory.Pointer<t$Foo>);
}