To completely override an existing bean definition in your webapp extension, in your webapp JAR extension's plugin.xml, you define a new bean with the exact same bean id as the bean you are overriding.

For example, suppose you want to override the priceListLookupService bean in ep-core/src/main/resources/spring/service/service.xml:

<bean id="priceListLookupService" 
        class="com.elasticpath.common.pricing.service.impl.PriceListLookupServiceImpl">
    <property name="plStackLookupStrategy" ref="plaStackLookupStrategy"/commerce-legacy/>
</bean>

In ep-core-plugin.xml in the ext-core module, you would add the following:

<import resource="classpath:spring/service/ext-service.xml"/commerce-legacy/>

Then you would create an ext-service.xml in the ext-core/resources/spring/service directory with the bean override:

<bean id="priceListLookupService" 
        class="com.elasticpath.extensions.common.pricing.service.impl.ExtPriceListLookupServiceImpl">
    <property name="plStackLookupStrategy" ref="plaStackLookupStrategy"/commerce-legacy/>
</bean>

However, you may want to change only the configuration parameters of an existing bean definition, or override just the implementation class. There is a way to so this without replacing the entire bean definition. To do this, you need to use the PluginBeanFactoryPostProcessor.

The com.elasticpath.commons.util.impl.PluginBeanFactoryPostProcessor class is an implementation of the Spring BeanFactoryPostProcessor interface. Spring invokes this after all of the configuration has been discovered and loaded in memory, but before the actual objects are created.

Below is a PluginBeanFactoryPostProcessor bean definition:

<bean class="com.elasticpath.commons.util.impl.PluginBeanFactoryPostProcessor">
  <property name="extensionBeanName" value="EXTENSION_BEAN_NAME"/commerce-legacy/>
  <property name="extensionClassName" value="EXTENSION_CLASS_NAME"/commerce-legacy/>
  <property name="propertyName" value="PROPERTY_NAME"/commerce-legacy/>
  <property name="propertyValue" ref="PROPERTY_VALUE"/commerce-legacy/>
</bean>

To override or extend an existing built-in bean, add a PluginBeanFactoryPostProcessor bean definition in your extension Spring configuration and specify the following properties:

For example, overriding the implementation class of priceListLookupService class could be done without copying any bean properties:

<bean class="com.elasticpath.commons.util.impl.PluginBeanFactoryPostProcessor">
    <property name="extensionBeanName" value="priceListLookupService"/commerce-legacy/>
    <property name="extensionClassName" value="com.elasticpath.extensions.common.pricing.service.impl.ExtPriceListLookupServiceImpl">
</bean>

To override multiple properties on a particular bean, use the propertiesMap property as follows:

<property name="propertiesMap">
    <map>
        <entry key="customerService" ref="customerService"/commerce-legacy/>
        <entry key="elasticPath" ref="elasticPath"/commerce-legacy/>
    </map>
</property>