org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'ldap' defined in URL [file:...../extensions/ldap/WEB-INF/ExtensionContext.xml]: Error setting property values; nested exception is org.springframework.beans.NotWritablePropertyException: Invalid property 'coreVersion' of bean class [com.kportal.extension.DefaultExtensionImpl]: Bean property 'coreVersion' is not writable or has an invalid setter method. Does the parameter type of the setter match the return type of the getter?

<bean id="ldap" class="com.kportal.extension.DefaultExtensionImpl" >
                <property name="libelle" value="LDAP.EXTENSION_LIBELLE" />
                <property name="version" value="1.0-RC-3" />
                <property name="coreVersion" value="6.0-RC-3" />
                <property name="description" value="LDAP.EXTENSION_DESCRIPTION" />
                <property name="logo" value="/resources/images/extension.png" />
                <property name="auteur" value="Kosmos" />
                <property name="etat" ref="ETAT_NON_ACTIF" />
        </bean>