Spring security using LDAP authentication without using manager-dn and manager-password

Question

I am using Spring Security for ldap authentication and have this configuration on my spring-security.xml

        <security:authentication-manager>
        <security:ldap-authentication-provider  
                user-search-filter="xxxxx" 
                user-search-base=""
                group-search-filter="xxxxx"
                group-search-base=""
                group-role-attribute="cn"
                role-prefix="ROLE_">
        </security:ldap-authentication-provider>
    </security:authentication-manager>

    <security:ldap-server url="ldap://servername54389/dc=..." manager-dn="xxxx" manager-password="xxxx" />

This works well for me. However, we cannot put manager-dn and manager-password like this in the xml. Is there a way to avoid putting manager-password in the code and still have it work? If I simply remove manager-dn and manager-password in the xml, it does not work and gives Access denied error.

Any details/help on this would be greatly appreciated