Order of properties in swagger definitions changes from run to run

Question

I use swagger-maven-plugin to generate swagger.json. However, I noticed that an order of properties changes from run to run. For example, it can be:

{
  ...
  "definitions" : {
    "MyClass1" : {
      "type" : "object",
      "properties" : {
        "name" : {
          "type" : "string"
        },
        "title" : {
          "type" : "string"
        },
        "description" : {
          "type" : "string"
        },
      }
    }
  }
  ...
}

and then after the next generation:

{
  ...
  "definitions" : {
    "MyClass1" : {
      "type" : "object",
      "properties" : {
        "description" : {
          "type" : "string"
        },
        "title" : {
          "type" : "string"
        },
        "name" : {
          "type" : "string"
        }
      }
    }
  }
  ...
}

My class in Java:

public interface MyClass1 {
   String getName();
   String getTitle();
   String getDescription();
}

Answer 1

It's impossible in Java Runtime to know the exact order of methods declared in a class. If you open java.lang.Class#getDeclaredMethods() (see https://docs.oracle.com/javase/8/docs/api/java/lang/Class.html#getDeclaredMethods--) you will see that The elements in the returned array are not sorted and are not in any particular order..

That's why Jackson can't do it for you.

However, there are 2 solutions:

1.You can use @JsonPropertyOrder annotation:

@JsonPropertyOrder({"name", "title", "description"})
public interface MyClass1 {
   String getName();
   String getTitle();
   String getDescription();
}

2.You can use a class with fields (field order is preserved)

public class MyClass1 {
   String name;
   String title;
   String description;
   //Getters skipped
}