diff --git a/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/clean/CleaningFunctions.java b/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/clean/CleaningFunctions.java
index 798eae4ddd..859fc074c3 100644
--- a/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/clean/CleaningFunctions.java
+++ b/dhp-workflows/dhp-graph-mapper/src/main/java/eu/dnetlib/dhp/oa/graph/clean/CleaningFunctions.java
@@ -16,7 +16,10 @@ import eu.dnetlib.dhp.schema.oaf.*;
 public class CleaningFunctions {
 
 	public static final String DOI_URL_PREFIX_REGEX = "(^http(s?):\\/\\/)(((dx\\.)?doi\\.org)|(handle\\.test\\.datacite\\.org))\\/";
+
 	public static final String ORCID_CLEANING_REGEX = ".*([0-9]{4}).*[-–—−=].*([0-9]{4}).*[-–—−=].*([0-9]{4}).*[-–—−=].*([0-9x]{4})";
+	public static final int ORCID_LEN = 19;
+
 	public static final String CLEANING_REGEX = "(?:\\n|\\r|\\t)";
 
 	public static final Set<String> PID_BLACKLIST = new HashSet<>();
@@ -86,7 +89,7 @@ public class CleaningFunctions {
 		} else if (value instanceof Organization) {
 			Organization o = (Organization) value;
 			if (Objects.isNull(o.getCountry()) || StringUtils.isBlank(o.getCountry().getClassid())) {
-				o.setCountry(qualifier("UNKNOWN", "Unknown", ModelConstants.DNET_COUNTRY_TYPE));
+				o.setCountry(qualifier(ModelConstants.UNKNOWN, "Unknown", ModelConstants.DNET_COUNTRY_TYPE));
 			}
 		} else if (value instanceof Relation) {
 			// nothing to clean here
@@ -153,12 +156,14 @@ public class CleaningFunctions {
 			if (Objects.isNull(r.getResourcetype()) || StringUtils.isBlank(r.getResourcetype().getClassid())) {
 				r
 					.setResourcetype(
-						qualifier("UNKNOWN", "Unknown", ModelConstants.DNET_DATA_CITE_RESOURCE));
+						qualifier(ModelConstants.UNKNOWN, "Unknown", ModelConstants.DNET_DATA_CITE_RESOURCE));
 			}
 			if (Objects.nonNull(r.getInstance())) {
 				for (Instance i : r.getInstance()) {
 					if (Objects.isNull(i.getAccessright()) || StringUtils.isBlank(i.getAccessright().getClassid())) {
-						i.setAccessright(qualifier("UNKNOWN", "not available", ModelConstants.DNET_ACCESS_MODES));
+						i
+							.setAccessright(
+								qualifier(ModelConstants.UNKNOWN, "not available", ModelConstants.DNET_ACCESS_MODES));
 					}
 					if (Objects.isNull(i.getHostedby()) || StringUtils.isBlank(i.getHostedby().getKey())) {
 						i.setHostedby(ModelConstants.UNKNOWN_REPOSITORY);
@@ -173,7 +178,7 @@ public class CleaningFunctions {
 				if (Objects.isNull(bestaccessrights)) {
 					r
 						.setBestaccessright(
-							qualifier("UNKNOWN", "not available", ModelConstants.DNET_ACCESS_MODES));
+							qualifier(ModelConstants.UNKNOWN, "not available", ModelConstants.DNET_ACCESS_MODES));
 				} else {
 					r.setBestaccessright(bestaccessrights);
 				}
@@ -227,7 +232,7 @@ public class CleaningFunctions {
 												.trim()
 												.toLowerCase()
 												.replaceAll(ORCID_CLEANING_REGEX, "$1-$2-$3-$4");
-											if (orcid.length() == 19) {
+											if (orcid.length() == ORCID_LEN) {
 												p.setValue(orcid);
 											} else {
 												p.setValue("");