Java bug generating proper formatting for date fields

Description

The Java client code being generated for fields defined with format 'date' in OAS3 and a pattern of "YYYY-MM-DD" are working properly. Specifically, even with explicitly setting the export configuration to use Java 11 JSR384 and use Jackson. there is no reference to Jackson in the java file and the Java type is java.util.Date, with no formatting and the getXXX method returns a long/integer.

Swagger-codegen version

The current version being provided on https://app.swaggerhub.com

Swagger declaration file content or url

birthdate:
type: string
format: date
pattern: "YYYY-MM-DD"
example: "1995-01-01"

Command line used for generation

Steps to reproduce

Related issues/PRs

Suggest a fix/enhancement

The only workaround is to manually alter the Java code generated by swagger code-gen with the following Jackson annotations. However, this is very brittle and breaks the general rule never to alter auto-generated code. It also means our CI/CD flow won't work automatically without reverting the workaround back to the broken code.

@JsonProperty("birthdate")
@JsonFormat (shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd")
private Date birthdate = null;

Start by reproducing the generated Java client from the supplied OAS3 birthdate declaration with Java 11 JSR384 and Jackson selected in the export configuration. Inspect the generated field and getter, then compare the output with the requested date representation; done means the generated client handles the date field and formatting without manual edits.