The StringParameterInjector only extracts the first value from the list of parameters:

if (values == null)
    return extractValue(null);
if (values.size() == 0)
    return extractValue(null);
return extractValue(values.get(0));

This should account for all parameters. Assume query parameters passed like: ?names=Foo&names=Bar. Both "Foo" and "Bar" should be processed here.