[BUG][java] function fromValue for enum model have wrong end if enumUnknownDefaultCase=true

[pawelgamrot]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
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Description

If set enumUnknowDefaultCase to true then additional enum (UNKNOWN_DEFAULT_OPEN_API("unknown_default_open_api");) is generated properly but fromValue function end with throw new IllegalArgumentException("Unexpected value '" + value + "'"); but should end with return UNKNOWN_DEFAULT_OPEN_API;

openapi-generator 5.4.0

Suggest a fix

in modelEnum.mustache replace:

public static {{{datatypeWithEnum}}}{{^datatypeWithEnum}}{{{classname}}}{{/datatypeWithEnum}} fromValue({{{dataType}}} value) {
    for ({{{datatypeWithEnum}}}{{^datatypeWithEnum}}{{{classname}}}{{/datatypeWithEnum}} b : {{{datatypeWithEnum}}}{{^datatypeWithEnum}}{{{classname}}}{{/datatypeWithEnum}}.values()) {
      if (b.value.equals(value)) {
        return b;
      }
    }
    {{#isNullable}}return null;{{/isNullable}}{{^isNullable}}throw new IllegalArgumentException("Unexpected value '" + value + "'");{{/isNullable}}
  }

with

public static {{{datatypeWithEnum}}}{{^datatypeWithEnum}}{{{classname}}}{{/datatypeWithEnum}} fromValue({{{dataType}}} value) {
    for ({{{datatypeWithEnum}}}{{^datatypeWithEnum}}{{{classname}}}{{/datatypeWithEnum}} b : {{{datatypeWithEnum}}}{{^datatypeWithEnum}}{{{classname}}}{{/datatypeWithEnum}}.values()) {
      if (b.value.equals(value)) {
        return b;
      }
    }
    {{#isNullable}}return null;{{/isNullable}}{{^isNullable}}{{#enumUnknownDefaultCase}}{{#allowableValues}}{{#enumVars}}{{#-last}}return {{{name}}};{{/-last}}{{/enumVars}}{{/allowableValues}}{{/enumUnknownDefaultCase}}{{^enumUnknownDefaultCase}}throw new IllegalArgumentException("Unexpected value '" + value + "'");{{/enumUnknownDefaultCase}}{{/isNullable}}
  }

[pawelgamrot]

The same change should be done in modelInnerEnum.mustache