public String getSystemUsername() {
        return systemUsername;
    }
Returns the system username that will be used when creating an LDAP connection used for authorization queries.
The user must have the ability to query for authorization data for any application user.
<p/>
Note that setting this property is not required if the calling LDAP Realm does not perform authorization
checks.

@return the system username that will be used when creating an LDAP connection used for authorization queries.
core/src/main/java/org/apache/shiro/realm/ldap/JndiLdapContextFactory.java