Ensure correct Input json property order (#93)

Default order is JDK-dependent, see
https://www.tedblob.com/jackson-serialization-order/

Author: jpraet

belgif-rest-problem/src/main/java/io/github/belgif/rest/problem/api/Input.java

@@ -3,6 +3,7 @@
 import java.util.Objects;
 
 import com.fasterxml.jackson.annotation.JsonInclude;
+import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 
 /**
  * Input model for {@link InputValidationIssue#getInputs()}.
@@ -19,6 +20,7 @@
  *
  * @param <V> the input value type
  */
+@JsonPropertyOrder({ "in", "name", "value" })
 public class Input<V> {
 
     private InEnum in;