@Entity
@Multitenant(MultitenantType.TABLE_PER_TENANT)
@TenantTableDiscriminator(type = TenantTableDiscriminatorType.SCHEMA, contextProperty = PersistenceUnitProperties.MULTITENANT_PROPERTY_DEFAULT)
public class UserAccount implements Serializable {
......
}

<persistence-unit name="GroupBuilderPU" transaction-type="RESOURCE_LOCAL">
        <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
        <class>Includes all tenant table class</class>
        <properties>
            <property name="eclipselink.cache.shared.default" value="false"/>
            <!-- container isn upcloud ??-->
             <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/?rewriteBatchedStatements=true&characterEncoding=UTF-8&connectionCollation=utf8_general_ci&zeroDateTimeBehavior=convertToNull&useUnicode=true&connectionCollation=utf8_general_ci&characterSetResults=utf8&characterEncoding=utf8&characterEncoding=UTF-8&characterSetResults=UTF-8"/>
            <property name="javax.persistence.jdbc.user" value="root"/>
            <property name="javax.persistence.jdbc.password" value="root"/>

            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
            <property name="eclipselink.ddl-generation" value="create-or-extend-tables"/>
            <property name="eclipselink.jdbc.batch-writing" value="JDBC"/>
            <property name="eclipselink.jdbc.batch-writing.size" value="1000"/>
            <property name="hibernate.connection.useUnicode" value="true"/>
            <property name="hibernate.connection.characterEncoding" value="UTF-8"/>
        </properties>
    </persistence-unit>

public static EntityManager createTenantSpecificEntityManager(){
        EntityManager em = Persistence.createEntityManagerFactory(GroupBuilderApp.PERSISTENCE_UNIT).createEntityManager(getProperties());

        return em;
    }

private static Map<String, Object> getProperties(){
        Map<String, Object> properties = new HashMap<>();
        properties.put("javax.persistence.jdbc.url", getDataBaseConnectionURL(COMPANY_NAME_AS_TENENT_ID));

        return properties;
    }
public static String getDataBaseConnectionURL(String schemaName){
        String str = "jdbc:mysql://localhost:3306/?rewriteBatchedStatements=true&characterEncoding=UTF-8&connectionCollation=utf8_general_ci&zeroDateTimeBehavior=convertToNull&useUnicode=true&connectionCollation=utf8_general_ci&characterSetResults=utf8&characterEncoding=utf8&characterEncoding=UTF-8&characterSetResults=UTF-8";//for testing purpose
        StringBuilder sb = new StringBuilder(str);
        sb.insert(sb.indexOf("?"), schemaName);
        return sb.toString();
    }

em = createTenantSpecificEntityManager();
em.getTransaction().begin();
       em.setProperty(EntityManagerProperties.MULTITENANT_PROPERTY_DEFAULT, GroupBuilderApp.COMPANY_NAME_AS_TENENT_ID);
.......
Do any operation here
.......
em.getTransaction().commit();
em.close();