Override hybris commonI18NService roundCurrency method

Question

Trying to override spring bean using Alias.

I want to over ride roundCurrency method of commonI18NService

OOTB definition

<alias alias="commonI18NService" name="defaultCommonI18NService"/>
<bean id="defaultCommonI18NService" class="de.hybris.platform.servicelayer.i18n.impl.DefaultCommonI18NService"  parent="abstractBusinessService">
    <property name="languageDao" ref="languageDao"/>
    <property name="currencyDao" ref="currencyDao"/>
    <property name="countryDao" ref="countryDao"/>
    <property name="regionDao" ref="regionDao"/>
    <property name="conversionStrategy" ref="conversionStrategy"/>
</bean>

Our custom code :-

public class DefaultCustomCommonI18NService extends DefaultCommonI18NService
{

    @Override
    public double roundCurrency(double value, int digits)
    {
      // custom logic
        return value;
    }
} 

Inject custom bean :-

<alias alias="commonI18NService" name="defaultCustomCommonI18NService"/>
<bean id="defaultCustomCommonI18NService" class="com.extended.service.impl.DefaultCustomCommonI18NService"  parent="defaultCommonI18NService"/>

But it throws exception on server startUP

INFO  [localhost-startStop-1] [HybrisContextFactory] Loading <<application>> spring config <master> from extension (saporderexchangeb2b) located in (saporderexchangeb2b-spring.xml) took: (121.4 ms)
WARN  [localhost-startStop-1] [CloseAwareApplicationContext] Exception encountered during context initialization - cancelling refresh attempt
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'listMergeBeanPostProcessor': Invocation of init method failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'commercePlaceOrderMethodHooksListMergeDirective' defined in class path resource [b2bapprovalprocess-spring.xml]: Cannot resolve reference to bean 'b2bApprovalBusinessProcessCreationPlaceOrderMethodHook' while setting bean property 'add'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'b2bApprovalBusinessProcessCreationPlaceOrderMethodHook' defined in class path resource [b2bapprovalprocess-spring.xml]: Cannot resolve reference to bean 'defaultB2BCreateOrderFromCartStrategy' while setting bean property 'businessProcessCreationStrategy'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultB2BCreateOrderFromCartStrategy' defined in class path resource [b2bapprovalprocess-spring.xml]: Cannot resolve reference to bean 'cloneAbstractOrderStrategy' while setting bean property 'cloneAbstractOrderStrategy'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultCloneAbstractOrderStrategy' defined in class path resource [order-spring.xml]: Cannot resolve reference to bean 'typeService' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultTypeService' defined in class path resource [servicelayer-spring.xml]: Cannot resolve reference to bean 'converterRegistry' while setting bean property 'converterRegistry'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'defaultConverterRegistry' defined in class path resource [servicelayer-spring.xml]: Unsatisfied dependency expressed through bean property 'commonI18NService': : No qualifying bean of type [de.hybris.platform.servicelayer.i18n.CommonI18NService] is defined: expected single matching bean but found 2: defaultCommonI18NService,defaultcustomCommonI18NService; nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [de.hybris.platform.servicelayer.i18n.CommonI18NService] is defined: expected single matching bean but found 2: defaultCommonI18NService,defaultcustomCommonI18NService
        at org.springframework.beans.factory.annotation.InitDestroyAnnotationBeanPostProcessor.postProcessBeforeInitialization(InitDestroyAnnotationBeanPostProcessor.java:136) ~[spring-beans-4.1.7.RELEASE.jar:4.1.7.RELEASE]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsBeforeInitialization(AbstractAutowireCapableBeanFactory.java:408) ~[spring-beans-4.1.7.RELEASE.jar:4.1.7.RELEASE]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1566) ~[spring-beans-4.1.7.RELEASE.jar:4.1.7.RELEASE]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:539) ~[spring-beans-4.1.7.RELEASE.jar:4.1.7.RELEASE]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476) ~[spring-beans-4.1.7.RELEASE.jar:4.1.7.RELEASE]

Answer 1

This is happening because the autowiring strategy of defaultConverterRegistry is byType:

<bean id="defaultConverterRegistry" ... autowire="byType" >

which means Spring found two candidates for commonI18NService bean defaultCommonI18NService and defaultcustomCommonI18NService hence don't know which one to inject.

I propose to make your defaultcustomCommonI18NService a primary bean to be the autowired by using primary="true", see

<bean id="defaultCustomCommonI18NService" class="com.extended.service.impl.DefaultCustomCommonI18NService"  parent="defaultCommonI18NService" primary="true" />