@Field
    public void setIdField(String idField) {
        this.idField = idField;
    }
Specify the field in the first Metadata that should be
used as the id field for the document.

@param idField
tika-pipes/tika-emitters/tika-emitter-solr/src/main/java/org/apache/tika/pipes/emitter/solr/SolrEmitter.java