I have hibernate.cfg.xml file inside my src file and I'm still getting this error. Please see my HibernateUtil class, errors and xml file. I tried most of solutions that other people posted in other treads.
Here is the screenshot of the structure:

import org.hibernate.SessionFactory;
import org.hibernate.cfg.AnnotationConfiguration;
public class HiberUtil {
    private static final SessionFactory sessionFactory;
    static {
        try {
            // Create the SessionFactory from standard (hibernate.cfg.xml) 
            // config file.
            sessionFactory = new AnnotationConfiguration().configure().buildSessionFactory();
        } catch (Throwable ex) {
            // Log the exception. 
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
        //        Configuration configuration = new Configuration().configure();
//        StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder().
//                applySettings(configuration.getProperties());
//        sessionFactory = configuration.buildSessionFactory(builder.build());
    }
    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
}
Here is the error:
Aug 06, 2017 10:40:29 PM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit>
INFO: HCANN000001: Hibernate Commons Annotations {4.0.4.Final}
Aug 06, 2017 10:40:29 PM org.hibernate.Version logVersion
INFO: HHH000412: Hibernate Core {4.3.1.Final}
Aug 06, 2017 10:40:29 PM org.hibernate.cfg.Environment <clinit>
INFO: HHH000206: hibernate.properties not found
Aug 06, 2017 10:40:29 PM org.hibernate.cfg.Environment buildBytecodeProvider
INFO: HHH000021: Bytecode provider name : javassist
Aug 06, 2017 10:40:29 PM org.hibernate.cfg.Configuration configure
INFO: HHH000043: Configuring from resource: /hibernate.cfg.xml
Aug 06, 2017 10:40:29 PM org.hibernate.cfg.Configuration getConfigurationInputStream
INFO: HHH000040: Configuration resource: /hibernate.cfg.xml
Initial SessionFactory creation failed.org.hibernate.HibernateException: /hibernate.cfg.xml not found
Exception in thread "JavaFX Application Thread" java.lang.ExceptionInInitializerError
Here is the hibernate.cfg.xml if you need this:
<hibernate-configuration>
     <session-factory>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/cokolada</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.connection.password">root</property>
        <property name="hibernate.show_sql">true</property>        
        <!-- Mapiranje klasa -->
        <mapping class="model.Cokolada"/>
    </session-factory>
</hibernate-configuration>