src/main/java/com/googlecode/objectify/repackaged/gentyref/TypeFactory.java
public static WildcardType wildcardExtends(Type upperBound) {
		if (upperBound == null) {
			throw new NullPointerException();
		}
		return new WildcardTypeImpl(new Type[]{upperBound}, new Type[]{});
	}
public static WildcardType wildcardExtends(Type upperBound) {
		if (upperBound == null) {
			throw new NullPointerException();
		}
		return new WildcardTypeImpl(new Type[]{upperBound}, new Type[]{});
	}
Creates a wildcard type with an upper bound.
<p>
For example <tt>wildcardExtends(String.class)</tt> returns the type <tt>? extends String</tt>.

@param upperBound Upper bound of the wildcard
@return A wildcard type