presto-spi/src/main/java/io/prestosql/spi/type/TypeSignatureParameter.java/TypeSignatureParameter/namedField
class TypeSignatureParameter:    public static TypeSignatureParameter namedField(String name, TypeSignature type)
    {
        return new TypeSignatureParameter(ParameterKind.NAMED_TYPE, new NamedTypeSignature(Optional.of(new RowFieldName(name)), type));
    }