Unwrap warning on size constraint annotation

[Sholto]

The @javax.validation.constraints.Size annotation on the following code:

@io.swagger.v3.oas.annotations.media.Schema(name = "band1Email")
@com.fasterxml.jackson.annotation.JsonProperty(value = "band1Email")
@javax.validation.constraints.Size(min = 1, max = 16777215, payload = javax.validation.valueextraction.Unwrapping.Unwrap.class, groups = { web.api.validation.Request.class, web.api.validation.Response.class })
public java.util.Optional<java.lang.String> getBand1Email() {
	return this.band1Email;
}

causes the following warning:

The constraint is marked for unwrapping but the annotation processor was not able to determine the unwrapped type. No further checks are performed.