how to inherit java.util.regex.Pattern class into smartgwt's source file?

[hell2heaven]

I tried to import java.util.regex.Pattern class in to a smartgwt's source file(rt.jar file is included in the JRE system library).But,I got the error message saying that

[ERROR] Line 155: No source code is available for type java.util.regex.Pattern; did you forget to inherit a required module?

How to get rid of this error message?Any help will be greatly appreciated...!Thanks in advance...

[hell2heaven]

I found this link useful to me...hope you do so...if you are also struck up here
http://code.google.com/docreader/#p=google-web-toolkit-doc-1-5&s=google-web-toolkit-doc-1-5&t=DevGuideJavaCompatibility