/oauth/v2/token?client_id=<client_id>&client_secret=<client_secret>&grant_type=password&username=<username>&password=<password>

client_id:          <your client id>
client_secret:      <your client secret>
grant_type:         password
username:           <your username>
password:           <your password>

/oauth/v2/token?grant_type=refresh_token&refresh_token=<refresh_token>&client_id=<client_id>&client_secret=<client_secret>

client_id:          <your client id>
client_secret:      <your client secret>
grant_type:         refresh_token
refresh_token:      <your refresh token>

{
    "access_token": "xxxxxxxxx",
    "expires_in": 84600,
    "token_type": "bearer",
    "scope": null,
    "refresh_token": "xxxxxxxxx"
}