Retrofit 500 Internal Server Error, Postman working
<p>I know there must've been 1000 posts like this one, but I searched for the mistake everywhere and could not find it, so i hope you guys can take a look and tell me if you notice something i am missing.</p>

<p><strong>Token class</strong></p>

<pre><code>public class Token {

public static final String POST = "tokens";

@SerializedName("token")
@Expose
private String token;
@SerializedName("role")
@Expose
private String role;

public String getToken() {
    return token;
}

public void setToken(String token) {
    this.token = token;
}

public String getRole() {
    return role;
}

public void setRole(String role) {
    this.role = role;
    }
}
</code></pre>

<p><strong>Entity class</strong></p>

<pre><code>public class Entity {

public Entity(){}

private Token mToken;

@SerializedName("email")
@Expose
private String mEmail;
@SerializedName("password")
@Expose
private String mPassword;

public Entity setFirstName(String firstName){return this;}
public Entity setLastName(String lastName){return this;}
public Entity setEmail(String email){
    mEmail = email;
    return this;
}
public Entity setPassword(String password){
    mPassword = password;
    return this;
}
public Entity setPasswordConfirmation(String passwordConfirmation){return this;}
public Entity setAddress(String address){return this;}
public Entity setCity(String city){return this;}
public Entity setCountryId(Integer countryId){return this;}
public Entity setToken(Token token){
    mToken = token;
    return this;
}

public String getEmail(){ return mEmail; }
public String getPassword(){ return mPassword; }
public Token getToken(Token token){ return mToken; }
}
</code></pre>

<p><strong>APIService</strong></p>

<pre><code> @POST(Token.POST)
Observable&lt;Token&gt; loginEntity(@Body Entity entity);
</code></pre>

<p><strong>API call</strong></p>

<pre><code>Observable&lt;Token&gt; loginEntityCall = RestClient.getInstance().service.loginEntity(loginEntity);
</code></pre>

<p><strong>What OkHttp outputs</strong></p>

<blockquote>
  <p>--> POST <a href="http://randomapi/api/v1/tokens" rel="nofollow noreferrer">http://randomapi/api/v1/tokens</a> http/1.1<br>
  Content-Type: application/json; charset=UTF-8<br>
  Content-Length: 55<br>
  {"email":"sample.user@example.com","password":"123456"}<br>
  --> END POST (55-byte body)    </p>
</blockquote>

<p>It returns </p>

<blockquote>
  <p>&lt;-- 500 Internal Server Error</p>
</blockquote>

<p><strong>Here is the copied value into postman</strong></p>

<p><a href="https://i.stack.imgur.com/SutlW.png" rel="nofollow noreferrer">postman</a></p>

<p>So postman gives OK, and my app gives me 500. I checked all values and i cannot find the mistake. :p</p>