Dex errors when compiling android_tutorial_pubsub

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I was able to compile android_tutorial_pubsub before, but something has changed recently and I get these weird dex exceptions from a fresh build:

   [dx] UNEXPECTED TOP-LEVEL EXCEPTION:
   [dx] java.lang.IllegalArgumentException: already added: Lorg/apache/xmlrpc/metadata/XmlRpcSystemImpl$1$1;
   [dx]     at com.android.dx.dex.file.ClassDefsSection.add(ClassDefsSection.java:123)
   [dx]     at com.android.dx.dex.file.DexFile.add(DexFile.java:163)
   [dx]     at com.android.dx.command.dexer.Main.processClass(Main.java:486)
   [dx]     at com.android.dx.command.dexer.Main.processFileBytes(Main.java:455)
   [dx]     at com.android.dx.command.dexer.Main.access$400(Main.java:67)
   [dx]     at com.android.dx.command.dexer.Main$1.processFileBytes(Main.java:394)
   [dx]     at com.android.dx.cf.direct.ClassPathOpener.processArchive(ClassPathOpener.java:245)
   [dx]     at com.android.dx.cf.direct.ClassPathOpener.processOne(ClassPathOpener.java:131)
   [dx]     at com.android.dx.cf.direct.ClassPathOpener.process(ClassPathOpener.java:109)
   [dx]     at com.android.dx.command.dexer.Main.processOne(Main.java:418)
   [dx]     at com.android.dx.command.dexer.Main.processAllFiles(Main.java:329)
   [dx]     at com.android.dx.command.dexer.Main.run(Main.java:206)
   [dx]     at com.android.dx.command.dexer.Main.main(Main.java:174)
   [dx]     at com.android.dx.command.Main.main(Main.java:95)

I'm not sure what they mean. There's about 16 of them. Any ideas?

I've done ./gradlew install on rosjava_core and I set the targets for android_gingerbread and android_tutorial_pubsub before running ../gradlew debug in the android_tutorial_pubsub directory.