org.hibernate.AnnotationException:No identifier specified for entity with XML Mapping

I'm working on a JPA program and had to write annotations for one class via xml-mapping. I wrote my model class like that:

ppackage model;

import javax.persistence.*;
import java.util.Date;
public class Reservierung {
	public Reservierung(Date datum, int praemienMeilenBonus, int preis, StatusInfo status, Zug zug, Strecke strecke, Benutzer benutzer, Zahlung zahlung) {
		this.datum = datum;
		this.praemienMeilenBonus = praemienMeilenBonus;
		this.preis = preis;
		this.status = status;
		this.zug = zug;
		this.strecke = strecke;
		this.benutzer = benutzer;
		this.zahlung = zahlung;
	}

	private Long ID;

	private Date datum;

	private int praemienMeilenBonus = 15;

	private int preis = 150;

	private StatusInfo status;
	private Zug zug;
	private Strecke strecke;
	private Benutzer benutzer;
	private Zahlung zahlung;

	public Date getDatum() {
		return datum;
	}

	public void setDatum(Date datum) {
		this.datum = datum;
	}

	public int getPraemienMeilenBonus() {
		return praemienMeilenBonus;
	}

	public void setPraemienMeilenBonus(int praemienMeilenBonus) {
		this.praemienMeilenBonus = praemienMeilenBonus;
	}

	public int getPreis() {
		return preis;
	}

	public void setPreis(int preis) {
		this.preis = preis;
	}

	public StatusInfo getStatus() {
		return status;
	}

	public void setStatus(StatusInfo status) {
		this.status = status;
	}

	public Zug getZug() {
		return zug;
	}

	public void setZug(Zug zug) {
		this.zug = zug;
	}

	public Strecke getStrecke() {
		return strecke;
	}

	public void setStrecke(Strecke strecke) {
		this.strecke = strecke;
	}

	public Benutzer getBenutzer() {
		return benutzer;
	}

	public void setBenutzer(Benutzer benutzer) {
		this.benutzer = benutzer;
	}

	public Zahlung getZahlung() {
		return zahlung;
	}

	public void setZahlung(Zahlung zahlung) {
		this.zahlung = zahlung;
	}

	public Long getID() {
		return ID;
	}

	public void setID(Long ID) {
		this.ID = ID;
	}
}

and after that I created the xml mapping file that I named orm:

?xml version="1.0" encoding="UTF-8"?>
<entity-mappings xmlns="http://java.sun.com/xml/ns/persistence/orm"
        version="2.0">
    <named-query name="Reservierung.findAll">
        <query>SELECT b FROM model.Reservierung b</query>
    </named-query>
    <entity name="Reservierung" class="model.Reservierung" >
        <table name="Reservierung" />
        <attributes>
            <id name="ID">
                <generated-value strategy="AUTO" />
            </id>
            <basic name="datum" />
            <basic name="praemienMeilenBonus" />
            <basic name="preis" />
            <basic name="StatusInfo" />

            <one-to-one name="strecke" />
            <one-to-one name="zug"/>
            <one-to-one name="benutzer"/>
            <transient name="zahlung"/>
        </attributes>
    </entity>
</entity-mappings>

finnaly I added the orm.xml and all the other files in my persistence.xml, which looks now like this

<persistence xmlns="http://xmlns.jcp.org/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence
             http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd"
  version="2.1">

  <persistence-unit name="westbahn">
      <description> Hibernate JPA Configuration Example</description>
      <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>

      <mapping-file>META-INF/orm.xml</mapping-file>

      <class>model.Bahnhof</class>
      <class>model.Benutzer</class>
      <class>model.Reservierung</class>
      <class>model.Einzelticket</class>
      <class>model.Preisstaffelung</class>
      <class>model.Sonderangebot</class>
      <class>model.Strecke</class>
      <class>model.Ticket</class>
      <class>model.Zeitkarte</class>
      <class>model.Zug</class>
      <class>model.Reservierung</class>

        <properties>
    <!--
          <property name="javax.persistence.jdbc.driver" value="com.mysql.cj.jdbc.Driver" />
          <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/westbahn?serverTimezone=UTC" />
          <property name="javax.persistence.jdbc.user" value="westbahnUser" />
          <property name="javax.persistence.jdbc.password" value="westbahnPassword" />
    -->
            <property name="javax.persistence.jdbc.driver" value="org.h2.Driver" />
            <property name="javax.persistence.jdbc.url"    value="jdbc:h2:file:./db/testing" />
            <property name="javax.persistence.jdbc.user" value="sa" />
            <property name="javax.persistence.jdbc.password" value="" />
            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
            <property name="hibernate.show_sql" value="false" />
            <property name="hibernate.hbm2ddl.auto" value="create-drop" />
            <!--<property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>-->
        </properties>
  </persistence-unit>
</persistence>

Till now I tried to see if the names where spelled wrong, if my class had some attributes that I didn't account for and also tried to change the name and finally added access="field" to the entity tag, but if I do so, I get another exception on top of the first one: org.hibernate.AnnotationException: Unable to load class defined in XML: model.Reservierung

Where did I do wrong?

edit:
Before the new orm.xml I had different mapping file named Reservierung.hbm.xml

<?xml version = "1.0" encoding = "utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
    <class name="model.Reservierung" table="Reservierung">
        <meta attribute = "class-description">
            This class contains the reservations
        </meta>

        <id name = "ID" type = "long" column = "ID">
            <generator class="native"/>
        </id>

        <property name = "datum" column = "datum" type = "date"> </property>
        <property name = "praemienMeilenBonus" column = "praemienMeilenBonus"> </property>
        <property name = "preis" column = "preis"> </property>
        <property name = "status" column = "status">
            <type name="org.hibernate.type.EnumType">
                <param name="enumClass">model.StatusInfo</param>
            </type>
        </property>
        <one-to-one name="strecke" />
        <one-to-one name="zug"/>
        <one-to-one name="benutzer"/>

    </class>
</hibernate-mapping>

I wasn't happy with it, so I trashed it and started from scratch with the orm.xml file

edit: what I did:
I made a constructor + getter and setter in all classes and now the exception changed to this:

java.lang.ClassCastException: class org.hibernate.mapping.SingleTableSubclass cannot be cast to class org.hibernate.mapping.RootClass (org.hibernate.mapping.SingleTableSubclass and org.hibernate.mapping.RootClass are in unnamed module of loader 'app')
	at org.hibernate.cfg.annotations.PropertyBinder.bind(PropertyBinder.java:214)
	at org.hibernate.cfg.annotations.PropertyBinder.makePropertyValueAndBind(PropertyBinder.java:205)
	at org.hibernate.cfg.AnnotationBinder.processElementAnnotations(AnnotationBinder.java:2283)
	at org.hibernate.cfg.AnnotationBinder.processIdPropertiesIfNotAlready(AnnotationBinder.java:976)
	at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:803)
	at org.hibernate.boot.model.source.internal.annotations.AnnotationMetadataSourceProcessorImpl.processEntityHierarchies(AnnotationMetadataSourceProcessorImpl.java:254)
	at org.hibernate.boot.model.process.spi.MetadataBuildingProcess$1.processEntityHierarchies(MetadataBuildingProcess.java:230)
	at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:273)
	at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:903)
	at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:934)
	at org.hibernate.jpa.HibernatePersistenceProvider.createEntityManagerFactory(HibernatePersistenceProvider.java:56)
	at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:79)
	at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:54)
	at main.Main.main(Main.java:47)
Exception in thread "main" java.lang.NullPointerException
	at main.Main.main(Main.java:64)