class Credentials {

    private final String username;
    private final String password;

    /**
     * Constructor
     *
     * @param username username
     * @param password password
     */
    public Credentials(String username, String password) {
        this.username = username;
        this.password = password;
    }

    /**
     * Method to get the size (username length + password length) of the credentials
     *
     * @return the size of the credentials
     */
    public int size() {
        return username.length() + password.length();
    }

    @Override
    public String toString() {
        return username + password;
    }

    @Override
    public boolean equals(Object o) {<FILL_FUNCTION_BODY>}

    @Override
    public int hashCode() {
        return Objects.hash(username, password);
    }
}

        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Credentials Credentials = (Credentials) o;
        return Objects.equals(username, Credentials.username)
                && Objects.equals(password, Credentials.password);
    
<no_super_class>