Field validation

#### Support plan

* *is this issue currently blocking your project?* (yes/no): yes
* *is this issue affecting a production system?* (yes/no): yes

#### Context

* *node version*: v18.14.2
* *module version*: 17.3.0
* *environment* (e.g. node, browser, native): node
* *used with* (e.g. hapi application, another framework, ...): both

#### How can we help?

```js
const NewUser = Joi.object()
.keys({
email: Joi.string()
.email()
.example("johndoe@example.com"),
name: Joi.string().example("john doe"),
username: Joi.when("email", {
is: Joi.exist(),
then: Joi.string().required(),
otherwise: Joi.optional()
}).example("johndoe"),
password: Joi.when("email", {
is: Joi.exist(),
then: Joi.string().required(),
otherwise: Joi.optional()
}).example("password"),
"first-name": Joi.string()
.allow(null)
.example("john"),
"communication-email": Joi.string()
.allow(null)
.example("johndoe@example.com"),
"phone-number": Joi.number()
.allow(null)
.example(9898989898),
"avatar-s3-key": Joi.string()
.allow(null)
.example("ace/2018-12/89a3fa9c-0b79-4140-b0ef-d1a35ea0b733/dog4.jpeg"),
"last-name": Joi.string()
.allow(null)
.example("doe"),
"dont-login": Joi.boolean()
.allow(null)
.example(true),
"avatar-url": Joi.string()
.uri()
.allow(null)
.example(
"https://thumbor-stg.assettype.com/ace/2018-12/89a3fa9c-0b79-4140-b0ef-d1a35ea0b733/dog4.jpeg"
),
"login-phone-number": Joi.string().example("+919898989898"),
otp: Joi.string()
.when("login-phone-number", {
is: Joi.exist(),
then: Joi.required(),
otherwise: Joi.optional()
})
.when("email", {
is: Joi.exist(),
then: Joi.required(),
otherwise: Joi.optional()
})
.example("12345"),
metadata: Joi.object()
.example({ "favorite-fruit": "papaya" })
.meta({ swagger: { deprecated: true } }),
active: Joi.boolean().example(true)
})
.xor("otp", "username", "password")
.or("login-phone-number", "email");
```

```
For payload:
{
"email":"povofev476@undewp.com",
"otp": "913676"
}
Response:
{
"message": "\"body.username\" is required,\"body.password\" is required"
}
```
username and password was initially to be mandatory, but when I have otp, username+password can be optional and vice versa. it can also allow all the three fields.