diff --git a/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/base/BaseCollectorPlugin.java b/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/base/BaseCollectorPlugin.java
index 21c896283..6140ed2c0 100644
--- a/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/base/BaseCollectorPlugin.java
+++ b/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/base/BaseCollectorPlugin.java
@@ -99,7 +99,7 @@ public class BaseCollectorPlugin implements CollectorPlugin {
 
 	private boolean filterXml(final String xml, final Set<String> excludedOpendoarIds, final AggregatorReport report) {
 		try {
-			final String id = DocumentHelper.parseText(xml).valueOf("//*[local-name='collection']/@opendoar_id").trim;
+			final String id = DocumentHelper.parseText(xml).valueOf("//*[local-name='collection']/@opendoar_id").trim();
 			return (StringUtils.isNotBlank(id) && !excludedOpendoarIds.contains("opendoar____::" + id.trim()));
 		} catch (final DocumentException e) {
 			log.error("Error parsing document", e);