On my Windows 10 system, with Java 9.0.4 and the head of trunk, I get something similar, but not identical.
compile: [javac] Compiling 143 source files to C:\Users\Bryan\derby\trunk\classes\client [javac] C:\Users\Bryan\derby\trunk\java\client\org\apache\derby\loc\client\clientmessagesProviderImpl.java:31: error: illegal character: '\u2039' [javac] public ResourceBundle getBundleΓÇï(String baseName, Locale locale) [javac] ^ [javac] C:\Users\Bryan\derby\trunk\java\client\org\apache\derby\loc\client\clientmessagesProviderImpl.java:31: error: ';' expected [javac] public ResourceBundle getBundleΓÇï(String baseName, Locale locale) [javac] ^ [javac] C:\Users\Bryan\derby\trunk\java\client\org\apache\derby\loc\client\clientmessagesProviderImpl.java:31: error: <identifier> expected [javac] public ResourceBundle getBundleΓÇï(String baseName, Locale locale) [javac] ^ [javac] C:\Users\Bryan\derby\trunk\java\client\org\apache\derby\loc\client\clientmessagesProviderImpl.java:31: error: cannot find symbol [javac] public ResourceBundle getBundleΓÇï(String baseName, Locale locale) [javac] ^ [javac] symbol: class locale [javac] location: class clientmessagesProviderImpl [javac] C:\Users\Bryan\derby\trunk\java\client\org\apache\derby\loc\client\clientmessagesProviderImpl.java:29: error: clientmessagesProviderImpl is not abstract and does not override abstract method getBundle(String,Locale) in ResourceBundleProvider [javac] public class clientmessagesProviderImpl implements clientmessagesProvider [javac] ^ [javac] C:\Users\Bryan\derby\trunk\java\client\org\apache\derby\loc\client\clientmessagesProviderImpl.java:33: error: cannot find symbol [javac] ResourceBundle bundle = ResourceBundle.getBundle(baseName, locale); [javac] ^ [javac] symbol: variable locale [javac] location: class clientmessagesProviderImpl [javac] C:\Users\Bryan\derby\trunk\java\client\org\apache\derby\loc\client\clientmessagesProviderImpl.java:34: error: return outside method [javac] return bundle; [javac] ^ [javac] 7 errors I see the message that Jenkins sees, but I also see some strange messages. I wonder if I've got some filesystem damage in my tree? I'll investigate further... bryan