diff --git a/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/GeoLocation.java b/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/GeoLocation.java
index 43af60286..1839fbd53 100644
--- a/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/GeoLocation.java
+++ b/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/GeoLocation.java
@@ -1,5 +1,6 @@
 package eu.dnetlib.dhp.schema.oaf;
 
+import com.fasterxml.jackson.annotation.JsonIgnore;
 import org.apache.commons.lang3.StringUtils;
 
 import java.io.Serializable;
@@ -36,7 +37,7 @@ public class GeoLocation implements Serializable {
         this.place = place;
     }
 
-
+    @JsonIgnore
     public boolean isBlank() {
         return StringUtils.isBlank(point) &&
                 StringUtils.isBlank(box) &&
diff --git a/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/KeyValue.java b/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/KeyValue.java
index 74d9f77bd..5a841b96f 100644
--- a/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/KeyValue.java
+++ b/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/KeyValue.java
@@ -1,5 +1,6 @@
 package eu.dnetlib.dhp.schema.oaf;
 
+import com.fasterxml.jackson.annotation.JsonIgnore;
 import org.apache.commons.lang3.StringUtils;
 
 import java.io.Serializable;
@@ -40,6 +41,7 @@ public class KeyValue implements Serializable {
         return isBlank()?"":String.format("%s::%s", key != null ? key.toLowerCase() : "", value != null ? value.toLowerCase() : "");
     }
 
+    @JsonIgnore
     public boolean isBlank() {
         return StringUtils.isBlank(key) && StringUtils.isBlank(value);
     }
diff --git a/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/Qualifier.java b/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/Qualifier.java
index 7e4660f4b..00ae88c52 100644
--- a/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/Qualifier.java
+++ b/dhp-schemas/src/main/java/eu/dnetlib/dhp/schema/oaf/Qualifier.java
@@ -1,5 +1,6 @@
 package eu.dnetlib.dhp.schema.oaf;
 
+import com.fasterxml.jackson.annotation.JsonIgnore;
 import org.apache.commons.lang3.StringUtils;
 
 import java.io.Serializable;
@@ -15,32 +16,36 @@ public class Qualifier implements Serializable {
         return classid;
     }
 
-    public void setClassid(String classid) {
+    public Qualifier setClassid(String classid) {
         this.classid = classid;
+        return this;
     }
 
     public String getClassname() {
         return classname;
     }
 
-    public void setClassname(String classname) {
+    public Qualifier setClassname(String classname) {
         this.classname = classname;
+        return this;
     }
 
     public String getSchemeid() {
         return schemeid;
     }
 
-    public void setSchemeid(String schemeid) {
+    public Qualifier setSchemeid(String schemeid) {
         this.schemeid = schemeid;
+        return this;
     }
 
     public String getSchemename() {
         return schemename;
     }
 
-    public void setSchemename(String schemename) {
+    public Qualifier setSchemename(String schemename) {
         this.schemename = schemename;
+        return this;
     }
 
     public String toComparableString() {
@@ -50,6 +55,8 @@ public class Qualifier implements Serializable {
                 schemeid != null ? schemeid : "",
                 schemename != null ? schemename : "");
     }
+
+    @JsonIgnore
     public boolean isBlank() {
         return StringUtils.isBlank(classid) &&
                 StringUtils.isBlank(classname) &&