Optional Enum field is not supported

[akomisarek]

For following input schema:

{
  "$schema": "http://json-schema.org/draft-04/schema#",
  "type": "object",
  "id": "http://cpp.moj.gov.uk/sjp/test-enum",
  "properties": {
    "enumField": {
      "enum": ["FIRST_OPTION", "SECOND_OPTION"]
    }
  },
  "additionalProperties": false
}

The generator generated following class:

package uk.gov.moj.cpp.sjp;

import java.lang.Override;
import java.lang.String;
import java.util.Optional;

public enum EnumField {
  FIRST_OPTION("FIRST_OPTION"),

  SECOND_OPTION("SECOND_OPTION");

  private final String value;

  EnumField(String value) {
    this.value = value;
  }

  @Override
  public String toString() {
    return value;
  }

  public static Optional<Optional<EnumField>> valueFor(final String value) {
    if(FIRST_OPTION.value.equals(value)) { return Optional.of(FIRST_OPTION); };
    if(SECOND_OPTION.value.equals(value)) { return Optional.of(SECOND_OPTION); };
    return Optional.empty();
  }
}

Which doesn't compile, because of valueFor method. Expected result is code which compiles, possibly returning just Optional as the additional Optional seems unnecessary.

[akomisarek]

I did quick investigation, actually it is caused by the plugin: SupportJavaOptionalsPlugin.

EnumGenerator buildValueForMethod uses createsType with additional Optional which is wrong.