JDK8: java.lang.ClassCastException: com.sun.activation.registries.MailcapFile cannot be cast to jakarta.activation.MailcapRegistry

[jbescos]

Describe the bug It was reported in mail: https://github.com/eclipse-ee4j/angus-mail/issues/37

Issue is explained here: https://github.com/eclipse-ee4j/angus-mail/issues/37#issuecomment-1293303298

To Reproduce Reproducer here with JDK8: https://github.com/eclipse-ee4j/angus-mail/issues/37#issue-1419900440

Expected behavior No error should be thrown.

Additional context To see the ClassCastException you just need to iterate over the list, for example:

	for (MailcapRegistry registry : dbv) {
	    System.out.println("Value: " + registry);
	    if (registry != null) {
	        System.out.println("Class: " + registry.getClass());
	    }
	}

[ERROR] Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.568 s <<< FAILURE! - in com.icegreen.greenmail.imap.commands.ImapProtocolTest
[ERROR] com.icegreen.greenmail.imap.commands.ImapProtocolTest.testUidSearchTextWithCharset  Time elapsed: 0.492 s  <<< ERROR!
java.lang.ClassCastException: com.sun.activation.registries.MailcapFile cannot be cast to jakarta.activation.MailcapRegistry
	at jakarta.activation.MailcapCommandMap.<init>(MailcapCommandMap.java:179)
	at jakarta.activation.CommandMap.getDefaultCommandMap(CommandMap.java:60)
	at jakarta.activation.DataHandler.getCommandMap(DataHandler.java:128)
	at jakarta.activation.DataHandler.getDataContentHandler(DataHandler.java:590)
	at jakarta.activation.DataHandler.writeTo(DataHandler.java:290)
	at jakarta.mail.internet.MimeUtility.getEncoding(MimeUtility.java:316)
	at jakarta.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1580)
	at jakarta.mail.internet.MimeMessage.updateHeaders(MimeMessage.java:2265)
	at jakarta.mail.internet.MimeMessage.saveChanges(MimeMessage.java:2225)
	at jakarta.mail.Transport.send(Transport.java:99)
	at com.icegreen.greenmail.util.GreenMailUtil.sendMimeMessage(GreenMailUtil.java:266)
	at com.icegreen.greenmail.util.GreenMailUtil.sendTextEmail(GreenMailUtil.java:256)
	at com.icegreen.greenmail.imap.commands.ImapProtocolTest.beforeEachTest(ImapProtocolTest.java:41)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:59)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:56)
	at org.junit.internal.runners.statements.RunBefores.invokeMethod(RunBefores.java:33)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:24)
	at com.icegreen.greenmail.junit.GreenMailRule$1.evaluate(GreenMailRule.java:63)
	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
	at org.junit.runners.BlockJUnit4ClassRunner$1.evaluate(BlockJUnit4ClassRunner.java:100)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:366)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:103)
	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:63)
	at org.junit.runners.ParentRunner$4.run(ParentRunner.java:331)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:79)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:329)
	at org.junit.runners.ParentRunner.access$100(ParentRunner.java:66)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:293)
	at org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:413)
	at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:377)
	at org.apache.maven.surefire.junit4.JUnit4Provider.executeWithRerun(JUnit4Provider.java:284)
	at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:248)
	at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:167)
	at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:456)
	at org.apache.maven.surefire.booter.ForkedBooter.execute(ForkedBooter.java:169)
	at org.apache.maven.surefire.booter.ForkedBooter.run(ForkedBooter.java:595)
	at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:581)

Otherwise the issue is hidden by this other exception:

java.lang.ArrayStoreException
	at java.lang.System.arraycopy(Native Method)
	at java.util.ArrayList.toArray(ArrayList.java:414)
	at jakarta.activation.MailcapCommandMap.<init>(MailcapCommandMap.java:181)
        ...

[jmehrens]

I was tempted to file an RFE on that unhelpful java.lang.ArrayStoreException. However, JDK11 has JDK-8204943: Improve message of ArrayStoreException so it would provide the details needed to get at the core issue. Since activation is removed in JDK9+ it might just be a JDK8 error.

[jbescos]

This is really odd.

The next will add in the list (this is how it is done currently):

MailcapRegistry registry = getImplementation().getByInputStream(clis);
if (registry != null) {
    v.add(registry);
}

The next will NOT add in the list:

MailcapRegistry registry = getImplementation().getByInputStream(clis);
if (registry != null && registry instanceof MailcapRegistry) {
    v.add(registry);
}

If this is evaluated as false: registry instanceof MailcapRegistry , then this line should throw a ClassCastException: MailcapRegistry registry = getImplementation().getByInputStream(clis);. But it is not throwing an exception there. It is thrown later when the list is iterated.

I have run the example with a javaagent that writes the bytecode of the classes in runtime and it shows that the class MailcapFile is the one that belongs to JDK8. This is consistent with the error.

[jbescos]

Solving it in https://github.com/eclipse-ee4j/angus-activation/pull/11

[lukasj]

done, I believe