presto-main/src/main/java/io/prestosql/metadata/TypeRegistry.java/TypeRegistry/addParametricType
class TypeRegistry:    public void addParametricType(ParametricType parametricType)
    {
        String name = parametricType.getName().toLowerCase(Locale.ENGLISH);
        checkArgument(!parametricTypes.containsKey(name), "Parametric type already registered: %s", name);
        parametricTypes.putIfAbsent(name, parametricType);
    }