Multipart nullable param with default required config should be none-required

[dfdgsdfg]

Cases

Param	Case1	Case2	Case3	Case4	Case5
requiredByDefaultConfig	false	TRUE	false	TRUE	false
requiredFromRequsetBody	false	false	TRUE	false	TRUE
property[nullable]	TRUE	TRUE	TRUE	false	false
-	-	-	-	-	-
Current 1.7.0 isRequired	❌	⭕️	❌	⭕️	⭕️
Current 1.7.0 isNullable	⭕️	⭕️	⭕️	❌	❌
-	-	-	-	-	-
Should be isRequired	❌	❌	❌	⭕️	⭕️
Should be isNullable	⭕️	⭕️	⭕️	❌	❌

Suggest

Case 1/2/3. If nullable, then what ever don't need required

If case3 is none-required, then also case2 should be none-required

• "param": { "nullable": true }
• @Part(name: 'param') Object? param

Case 4/5. If not nullable, then required

• "param": { }
• @Part(name: 'param') required Object param

Motivation

Explicit nullable should be generated as nullable without required regardless of the default config. What do you think?

Ref

https://swagger.io/docs/specification/describing-request-body/ https://github.com/trevorwang/retrofit.dart/issues/666