[BUG][JAVA] Deserialization of array with uniqueItems=true doesn't preserve order

After https://github.com/OpenAPITools/openapi-generator/issues/5254 was fixed and merged, when using Jackson, arrays with uniqueItems=true gets deserialized to HashSet rather than LinkedHashSet, thus not preserving order as expected.

Even though the field (myProp) is initialized to an empty LinkedHashSet, it is promptly overwritten with a regular HashSet given that there is no deserialization-hint (@JsonDeserialize(as = LinkedHashSet.class)) on the setMyProp-method. The method invoked looks like this:

  @JsonProperty(JSON_PROPERTY_MY_PROP)
  @JsonInclude(value = JsonInclude.Include.ALWAYS)
  public void setMyProp(Set<SomeEnum> myProp) {
    this.myProp = myProp;
  }

and thus there is no way for Jackson to understand that order needs to be preserved.

This issue is present in version 5.2.1

[borsch]

@MelleD yep

[borsch]

@MelleD I spent some time googling possible solution how to keep both JsonNullable & LinkedHashSet, but haven’t found anything yet. Here is a solution that I’ve mentioned before - skip @JsonDeserializer for JsonNullable fields

https://github.com/OpenAPITools/openapi-generator/pull/11495