CAS Attribute Release for Collections

When my client app calls CAS's /p3/serviceValidate endpoint I am having trouble getting multi-valued attributes to be considered as a Collection rather than just a single-valued string attribute. The client app receives the following message back from CAS and the issue is the 'authorities' attribute is a comma separated value rather than multiple xml elements:

Spring Client - Receiving This From CAS Server

<cas:serviceResponse xmlns:cas='http://ift.tt/1jNd6ZE'>
  <cas:authenticationSuccess>
    <cas:user>srowatt</cas:user>
    <cas:attributes>
      <cas:firstname>Shane</cas:firstname>                       
      <cas:authorities>ROLE_INNOADVERT,ROLE_INNOADVERT_ADMIN</cas:authorities>
      <cas:lastname>Rowatt</cas:lastname>
      <cas:username>srowatt</cas:username>
    </cas:attributes>
  </cas:authenticationSuccess>
</cas:serviceResponse>

Spring Client - Expecting This From CAS Server

<cas:serviceResponse xmlns:cas='http://ift.tt/1jNd6ZE'>
  <cas:authenticationSuccess>
    <cas:user>srowatt</cas:user>
    <cas:attributes>
      <cas:firstname>Shane</cas:firstname>                       
      <cas:authorities>ROLE_ROLE_INNOADVERT</cas:authorities>
      <cas:authorities>ROLE_INNOADVERT_ADMIN</cas:authorities>
      <cas:lastname>Rowatt</cas:lastname>
      <cas:username>srowatt</cas:username>
    </cas:attributes>
  </cas:authenticationSuccess>
</cas:serviceResponse>

CAS Server - User and Attributes Table

Below is the CAS Database Table with some sample values as comments:

CREATE TABLE users (
    username character varying(50) NOT NULL,  -- srowatt
    password character varying(50) NOT NULL,  -- 
    active bit(1) NOT NULL,                   -- 1
    firstname character varying,              -- shane
    lastname character varying,               -- rowatt
    authorities character varying             -- ROLE_ROLE_INNOADVERT,ROLE_INNOADVERT_ADMIN
)

CAS Server - deployerConfigContext.xml

This is the important bean defs on the CAS Server side that tells CAS which attributes to put in the serviceValdidate response:

<bean id="primaryPrincipalResolver"
      class="org.jasig.cas.authentication.principal.PersonDirectoryPrincipalResolver" >
    <property name="attributeRepository" ref="attributeRepository" />
</bean>

<bean id="attributeRepository"
      class="org.jasig.services.persondir.support.jdbc.SingleRowJdbcPersonAttributeDao">
    <constructor-arg index="0" ref="dataSource" />
    <constructor-arg index="1" value="SELECT * FROM users WHERE {0}" />
    <property name="queryAttributeMapping">
        <map>
            <entry key="username" value="username" />
        </map>
    </property>
    <property name="resultAttributeMapping">
        <map>
            <entry key="username" value="username" />
            <entry key="firstname" value="firstname" />
            <entry key="lastname" value="lastname" />
            <entry key="authorities" value="authorities"/>
        </map>
    </property>
</bean>

On my spring client app side I'm using the GrantedAuthorityFromAssertionAttributesUserDetailsService class to pick the 'authorities' attribute and inject the values as Spring Authorities and hence why I want this attribute to be a collection (not a csv).

@Bean
public AuthenticationUserDetailsService<CasAssertionAuthenticationToken> authenticationUserDetailsService() {
    String[] attributes = new String[] {
        "authorities"
    };
    GrantedAuthorityFromAssertionAttributesUserDetailsService userDetailsService =
        new GrantedAuthorityFromAssertionAttributesUserDetailsService(attributes);
    return userDetailsService;
}

I'm not sure what magic I'm missing to tell CAS should treat 'authorities' as a collection and not just a string.