public Multimap<String, String> getServiceMappingAsMultimap() {
    Multimap<String, String> result = ArrayListMultimap.create();
    for (KerberosKeytabServiceMappingEntity mappingEntity : serviceMapping) {
      result.put(mappingEntity.getServiceName(), mappingEntity.getComponentName());
    }
    return result;
  }
Service mappings must be fetched {@link FetchType#EAGER} since they are
required when processing {@link KerberosKeytabPrincipalEntity} instances
and turning them into {@link ResolvedKerberosPrincipal}.
ambari-server/src/main/java/org/apache/ambari/server/orm/entities/KerberosKeytabPrincipalEntity.java