намери решението с помощта на Spring Expression Language
<bean id="mongoTemplate" class="org.springframework.data.document.mongodb.MongoTemplate">
<constructor-arg name="mongo" ref="mongo"/>
<constructor-arg name="databaseName" value="${mongodb.dbname}"/>
<constructor-arg name="userCredentials" ref="mongoCredentials"/>
</bean>
<bean id="mongoCredentials" class="org.springframework.data.authentication.UserCredentials">
<property name="username" value="#{mongoURI.username}" />
<property name="password" value="#{new java.lang.String(mongoURI.password)}" />
</bean>
<bean class="com.mongodb.MongoURI" id="mongoURI">
<constructor-arg value="${mongodb.url}" />
</bean>
<bean class="com.mongodb.Mongo" id="mongo">
<constructor-arg ref="mongoURI" />
</bean>