Several illegal access warnings when using Java 9

[wvreeven]

Several warnings are logged when XStream is used in Java 9. FYI I am using Java 9.0.1 that recently was released. So far I have seen these:

[junit] WARNING: An illegal reflective access operation has occurred
[junit] WARNING: Illegal reflective access by com.thoughtworks.xstream.core.util.Fields (file:lib/compile/xstream-1.4.9.jar) to field java.util.TreeMap.comparator
[junit] WARNING: Please consider reporting this to the maintainers of com.thoughtworks.xstream.core.util.Fields
[junit] WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
[junit] WARNING: All illegal access operations will be denied in a future release

[junit] WARNING: An illegal reflective access operation has occurred
[junit] WARNING: Illegal reflective access by com.thoughtworks.xstream.core.util.Fields (file:lib/compile/xstream-1.4.9.jar) to field java.lang.reflect.Proxy.h
[junit] WARNING: Please consider reporting this to the maintainers of com.thoughtworks.xstream.core.util.Fields
[junit] WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
[junit] WARNING: All illegal access operations will be denied in a future release

[junit] WARNING: An illegal reflective access operation has occurred
[junit] WARNING: Illegal reflective access by com.thoughtworks.xstream.converters.reflection.AbstractAttributedCharacterIteratorAttributeConverter (file:lib/compile/xstream-1.4.9.jar) to method java.text.AttributedCharacterIterator$Attribute.getName()
[junit] WARNING: Please consider reporting this to the maintainers of com.thoughtworks.xstream.converters.reflection.AbstractAttributedCharacterIteratorAttributeConverter
[junit] WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
[junit] WARNING: All illegal access operations will be denied in a future release

[junit] WARNING: An illegal reflective access operation has occurred
[junit] WARNING: Illegal reflective access by com.thoughtworks.xstream.core.util.Fields (file:lib/compile/xstream-1.4.9.jar) to field java.awt.font.TextAttribute.instanceMap
[junit] WARNING: Please consider reporting this to the maintainers of com.thoughtworks.xstream.core.util.Fields
[junit] WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
[junit] WARNING: All illegal access operations will be denied in a future release

The simple workaround for this is to add these command line options to the invocation of java:

--add-opens java.base/java.util=ALL-UNNAMED --add-opens java.base/java.lang.reflect=ALL-UNNAMED --add-opens java.base/java.text=ALL-UNNAMED --add-opens java.desktop/java.awt.font=ALL-UNNAMED

However, this is not a proper solution of course. Please revise the code and fix the warnings. Many thanks!

[joehni]

Duplicate of #101