Switch from HashSet to LinkedHashSet for uniqueItems arrays to preserve order #159
Description
Hey there!
I'm not sure if this has come up before, but the use of a HashSet to implement a list of unique items does not guarantee the order is preserved. Unfortunately I believe JS (and in turn JSON) assume the list order should be preserved.
I've run into a case where something I've defined as a unique list of strings has unpredictable order when I try to use the POJOs generated by jsonschema2pojo.
For example, this schema:
{
"$schema": "http://json-schema.org/draft-04/schema",
"id": "#address",
"title": "Address",
"description": "A basic physical address",
"javaType": "com.awesome.mq.types.Address",
"type": "object",
"properties": {
"first_name": {"type": "string", "description": "First name of addressee"},
"middle_name": {"type": "string", "description": "Middle name of addressee"},
"last_name": {"type": "string", "description": "Last name of addressee"},
"street_address": {
"type": "array",
"items": {
"type": "string"
},
"minItems": 1,
"uniqueItems": true
},
"locality": { "description": "City, Town, Village, etc.", "type": "string" },
"region": { "description": "State or Province", "type": "string"},
"postal_code": { "type": "string" },
"country_code": { "type": "string" },
"region_code": { "type": "string" },
"phone": { "type": "string", "format": "phone"}
},
"required": ["addressee","street_address", "locality", "region", "postal_code", "country_code"]
}
Can lead to unpredictable ordering in the street_address list. This is not ideal for cases where you might want to print a shipping label, or something else where the order of the street address lines matter.
Obviously, the schema could be modified to have "street_address_1", "street_address_2", etc., but that seems like a hack rather than an ideal solution.
Is there a reason to use a HashSet over a LinkedHashSet? I believe a LinkedHashSet will preserve insertion order and does not incur the same performance hit as a TreeSet.
Am I correct in thinking that a change to jsonschema2pojo-core/src/main/java/org/jsonschema2pojo/rules/DefaultRule.java is enough to make this happen?
Forgive me if this has been asked a million times before.
Thanks!