input BikeInput {
    type: BikeType!
    brand: String!
    size: String!
    year: Int!
    price: BigDecimal
}

public class BikeInputTO {

    private BikeTypeTO type;
    private String brand;
    private String size;
    private Integer year;
    private String price;
...
}

public class BikeInputTO {

    @javax.validation.constraints.NotNull
    private BikeTypeTO type;
    @javax.validation.constraints.NotNull
    private String brand;
    @javax.validation.constraints.NotNull
    private String size;
    @javax.validation.constraints.NotNull
    private Integer year;
    private String price;
...
}