[kosinus]

Not even that is enough. My train of thought was: "This is the Java thing, right?" But I wasn't sure, and it's not mentioned anywhere in the opening paragraph of that page either. Java is not mentioned until "The GWT SDK contains the Java API libraries, compiler, and development server."

[jzaruba]

That might be on purpose. Way too many people (even seasoned Java pros) tend to dismiss GWT based on the WRONG assumption that "GWT runs on Java". Not mentioning Java in the very first sentence might by an attempt to avoid this seemingly minor yet critically important misconception.