presto-spi/src/main/java/io/prestosql/spi/type/DecimalType.java/DecimalType/buildTypeParameters
class DecimalType:    private static List<TypeSignatureParameter> buildTypeParameters(int precision, int scale)
    {
        List<TypeSignatureParameter> typeParameters = new ArrayList<>();
        typeParameters.add(TypeSignatureParameter.numericParameter(precision));
        typeParameters.add(TypeSignatureParameter.numericParameter(scale));
        return unmodifiableList(typeParameters);
    }