diff --git a/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/AlternateIdentifier.java b/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/AlternateIdentifier.java
index ca15fe1..e48a564 100644
--- a/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/AlternateIdentifier.java
+++ b/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/AlternateIdentifier.java
@@ -1,9 +1,9 @@
 package eu.dnetlib.dhp.schema.dump.oaf;
 
-import com.github.imifou.jsonschema.module.addon.annotation.JsonSchema;
-
 import java.io.Serializable;
 
+import com.github.imifou.jsonschema.module.addon.annotation.JsonSchema;
+
 public class AlternateIdentifier implements Serializable {
     @JsonSchema(description="The scheme of the identifier. It can be a persistent identifier (i.e. doi). If it is present in the alternate identifiers " +
             "it means it has not been forged by an authority for that pid. For example we collect metadata from an institutional repository that provides " +
diff --git a/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/AuthorPidSchemeValue.java b/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/AuthorPidSchemeValue.java
index d2db604..3439514 100644
--- a/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/AuthorPidSchemeValue.java
+++ b/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/AuthorPidSchemeValue.java
@@ -1,9 +1,9 @@
 package eu.dnetlib.dhp.schema.dump.oaf;
 
-import com.github.imifou.jsonschema.module.addon.annotation.JsonSchema;
-
 import java.io.Serializable;
 
+import com.github.imifou.jsonschema.module.addon.annotation.JsonSchema;
+
 public class AuthorPidSchemeValue implements Serializable {
 
     @JsonSchema(description="The author's pid scheme.  OpenAIRE currently supports 'ORCID'")
diff --git a/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/Measure.java b/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/Measure.java
index ebfbf24..4c86001 100644
--- a/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/Measure.java
+++ b/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/Measure.java
@@ -1,10 +1,11 @@
 package eu.dnetlib.dhp.schema.dump.oaf;
 
+import java.io.Serializable;
+
+import org.apache.commons.lang3.StringUtils;
+
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.github.imifou.jsonschema.module.addon.annotation.JsonSchema;
-import org.apache.commons.lang3.StringUtils;
-
-import java.io.Serializable;
 
 public class Measure implements Serializable {
     @JsonSchema(description = "The measure (i.e. popularity)")
@@ -41,4 +42,4 @@ public class Measure implements Serializable {
         return StringUtils.isBlank(key) && StringUtils.isBlank(value);
     }
 
-}
\ No newline at end of file
+}
diff --git a/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/SubjectSchemeValue.java b/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/SubjectSchemeValue.java
index 58a6224..9228088 100644
--- a/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/SubjectSchemeValue.java
+++ b/src/main/java/eu/dnetlib/dhp/schema/dump/oaf/SubjectSchemeValue.java
@@ -1,9 +1,9 @@
 package eu.dnetlib.dhp.schema.dump.oaf;
 
-import com.github.imifou.jsonschema.module.addon.annotation.JsonSchema;
-
 import java.io.Serializable;
 
+import com.github.imifou.jsonschema.module.addon.annotation.JsonSchema;
+
 public class SubjectSchemeValue implements Serializable {
     @JsonSchema(description="OpenAIRE subject classification scheme (https://api.openaire.eu/vocabularies/dnet:subject_classification_typologies).")
     private String scheme;