Going by the example at link it should be
<requestHandler name="/dataimport" class="org.apache.solr.handler.dataimport.DataImportHandler">
.........
<lst name="defaults">
<str name="config">data-config.xml</str>
<str name="update.chain">uuid</str>
</lst>
</requestHandler>
<updateRequestProcessorChain name="uuid">
<processor class="solr.UUIDUpdateProcessorFactory">
<str name="fieldName">uuid</str>
</processor>
<processor class="solr.RunUpdateProcessorFactory" />
</updateRequestProcessorChain>