As you are getting up to speed with the command line option you get with the Oracle Web Service stack, you may ran into the following error message (hopefully, you will be able to google this post) : "method java.util.Collections.emptyList with signature ()Ljava.util.List; was not found."
As the string is directly coming back from the java.lang.NoSuchMethodError exception, there is little to be done about it, other that checking that you have pre-requist before to get started. A better error message would have been "JAVA 5 or higher required".
If you ran into this issue, the simplest test to perform is to check the version of the JDK you are getting in your environment ($ java -version will do it).
I guess it's why I am using the ant task instead of the command line option, those days...
Hope it save some of you some time some day.