presto-main/src/main/java/io/prestosql/metadata/Signature.java/Signature/withVariadicBound
class Signature:    public static TypeVariableConstraint withVariadicBound(String name, String variadicBound)
    {
        return new TypeVariableConstraint(name, false, false, variadicBound, ImmutableSet.of(), ImmutableSet.of());
    }