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  1. JDK
  2. JDK-8244090

public lookup should find public members of public exported types




      In Jetty 10, we use method handles in the WebSocket implementation.

      We need to scan WebSocket EndPoint application classes (MyEndPoint) for annotated methods whose signature may vary and may take application classes, for example `@OnMessage void onMessage(Session s, MyString m)` where @OnMessage and Session are JSR 356 classes and MyEndPoint and MyString are application classes.

      It may be possible that the same web application is deployed twice, perhaps with different configurations.

      Therefore we have:
      * class "Impl" is the Jetty implementation class that creates
      MethodHandle.Lookup, loaded by serverClassLoader (and in a named JPMS module - although modules do not seem to matter)
      * class MyEndPoint and MyString are in webapp1's WEB-INF/classes, loaded by webClassLoader1 in an unnamed JPMS module
      * class MyEndPoint and MyString are also in webapp2's WEB-INF/classes, loaded by webClassLoader2 in another unnamed JPMS module

      Class Impl does this:
      MethodHandles.publicLookup().in(endPointClass).findVirtual(...), where
      "endPointClass" is class MyEndPoint loaded by the web class loader
      (either webClassLoader1 or webClassLoader2).

      We must call .in() to separate the 2 web applications (failing to call
      .in() results in linkage errors).

      Calling publicLookup().in() works in Java 11-13.

      In Java 14, it does not work anymore.
      The reason seems to stem from the fixes for

      In particular, in Java 14 publicLookup() returns a Lookup with
      mode=UNCONDITIONAL (but not PUBLIC? Is this intended?) and
      Lookup.lookupClassOrNull() returns Object.class rather than the class passed to .in() - like it was doing in Java 11.

      A reproducer project is attached.

      Make sure that classes from module1 are compiled into module1/classes and run it from the root with:

      java --class-path module2/classes org.module2.Main


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              mchung Mandy Chung
              sbordet Simone Bordet
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