Configuration conf = new Configuration().configure();   

configuring from resource: /hibernate.cfg.xml
Configuration resource: /hibernate.cfg.xml
Reading mappings from resource : Client.hbm.xml
Error parsing XML: XML InputStream(1) Document is invalid: no grammar found.
Error parsing XML: XML InputStream(1) Document root element "hibernate-mapping", must match DOCTYPE root "null".

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
    <class dynamic-insert="false" dynamic-update="false" mutable="true"
    name="icmmclientsmanager.Client"
    optimistic-lock="version"
    polymorphism="implicit"
    select-before-update="false" table="Clients">
        <id column="cId" name="cid">
            <generator class="identity"/>
        </id>
        <property column="cName" name="cName"/>
        <property column="cAddress" name="cAddress"/>
    </class>
</hibernate-mapping>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory name="session1">
        <property name="hibernate.dialect">
            org.hibernate.dialect.DerbyDialect
        </property>
        <property name="hibernate.connection.driver_class">
            com.mysql.jdbc.Driver
        </property>
        <property name="hibernate.connection.url">
            jdbc:mySql://localhost:3306/ICMMDev
        </property>
        <property name="hibernate.connection.username">
            root
        </property>
        <property name="hibernate.connection.password">
            password
        </property>
        <property name="hibernate.show_sql">
            true
        </property>
        <property name="hibernate.current_session_context_class">
            thread
        </property>
        <mapping resource="Client.hbm.xml"/>
    </session-factory>
</hibernate-configuration>