presto-client/src/main/java/io/prestosql/client/NamedClientTypeSignature.java/NamedClientTypeSignature/NamedClientTypeSignature
class NamedClientTypeSignature:    @JsonCreator
    public NamedClientTypeSignature(
            @JsonProperty("fieldName") Optional<RowFieldName> fieldName,
            @JsonProperty("typeSignature") ClientTypeSignature typeSignature)
    {
        this.fieldName = requireNonNull(fieldName, "fieldName is null");
        this.typeSignature = requireNonNull(typeSignature, "typeSignature is null");
    }