added serialVersionUID

src/main/java/eu/dnetlib/dhp/schema/oaf/AccessRight.java

@@ -8,6 +8,7 @@ import java.util.Optional;
  */
 public class AccessRight extends Qualifier {
 
+	private static final long serialVersionUID = -8945177777173510134L;
 	private OpenAccessRoute openAccessRoute;
 
 	public OpenAccessRoute getOpenAccessRoute() {

src/main/java/eu/dnetlib/dhp/schema/oaf/Author.java

@@ -6,6 +6,7 @@ import java.util.*;
 
 public class Author implements Serializable {
 
+	private static final long serialVersionUID = 1625492739044457437L;
 	private String fullname;
 
 	private String name;

src/main/java/eu/dnetlib/dhp/schema/oaf/Context.java

@@ -5,6 +5,8 @@ import java.io.Serializable;
 import java.util.List;
 
 public class Context implements Serializable {
+
+	private static final long serialVersionUID = -778899398223144398L;
 	private String id;
 
 	private List<DataInfo> dataInfo;

src/main/java/eu/dnetlib/dhp/schema/oaf/Country.java

@@ -5,6 +5,7 @@ import java.util.Objects;
 
 public class Country extends Qualifier {
 
+	private static final long serialVersionUID = 1587334433446567175L;
 	private DataInfo dataInfo;
 
 	public DataInfo getDataInfo() {

src/main/java/eu/dnetlib/dhp/schema/oaf/DataInfo.java

@@ -6,6 +6,8 @@ import java.util.Objects;
 
 public class DataInfo implements Serializable {
 
+	private static final long serialVersionUID = -277099962930866451L;
+
 	private Boolean invisible = false;
 	private Boolean inferred;
 	private Boolean deletedbyinference = false;

src/main/java/eu/dnetlib/dhp/schema/oaf/Dataset.java

@@ -8,6 +8,7 @@ import eu.dnetlib.dhp.schema.common.ModelConstants;
 
 public class Dataset extends Result implements Serializable {
 
+	private static final long serialVersionUID = 916526716184645549L;
 	private Field<String> storagedate;
 
 	// candidate for removal

src/main/java/eu/dnetlib/dhp/schema/oaf/Datasource.java

@@ -6,9 +6,6 @@ import java.util.List;
 
 public class Datasource extends OafEntity implements Serializable {
 
-	/**
-	 *
-	 */
 	private static final long serialVersionUID = 1019089598408414496L;
 
 	@Deprecated

src/main/java/eu/dnetlib/dhp/schema/oaf/EoscIfGuidelines.java

@@ -12,6 +12,7 @@ import org.apache.commons.lang3.StringUtils;
  */
 public class EoscIfGuidelines implements Serializable {
 
+    private static final long serialVersionUID = -2166497471601245048L;
     /**
      * EOSC-IF local code. Later on it could be populated with a PID (e.g. DOI), but for the time being we stick to
      * a more loose definition.

src/main/java/eu/dnetlib/dhp/schema/oaf/ExternalReference.java

@@ -6,6 +6,8 @@ import java.util.List;
 import java.util.Objects;
 
 public class ExternalReference implements Serializable {
+
+	private static final long serialVersionUID = -3711445600549155961L;
 	// source
 	private String sitename;
 

src/main/java/eu/dnetlib/dhp/schema/oaf/ExtraInfo.java

@@ -5,6 +5,8 @@ import java.io.Serializable;
 import java.util.Objects;
 
 public class ExtraInfo implements Serializable {
+
+	private static final long serialVersionUID = 8689244676887698486L;
 	private String name;
 
 	private String typology;

src/main/java/eu/dnetlib/dhp/schema/oaf/Field.java

@@ -6,6 +6,7 @@ import java.util.Objects;
 
 public class Field<T> implements Serializable {
 
+	private static final long serialVersionUID = -4255501306375330131L;
 	private T value;
 
 	private DataInfo dataInfo;

src/main/java/eu/dnetlib/dhp/schema/oaf/GeoLocation.java

@@ -9,6 +9,7 @@ import com.fasterxml.jackson.annotation.JsonIgnore;
 
 public class GeoLocation implements Serializable {
 
+	private static final long serialVersionUID = 8096534610208458404L;
 	private String point;
 
 	private String box;

src/main/java/eu/dnetlib/dhp/schema/oaf/H2020Classification.java

@@ -21,8 +21,9 @@ import java.util.Objects;
  * - private String level3 to store the information about the level3 of the classification
  * - private String classification to store the entire classification related to the programme
  */
-
 public class H2020Classification implements Serializable {
+
+	private static final long serialVersionUID = 1062734689288369769L;
 	private H2020Programme h2020Programme;
 	private String level1;
 	private String level2;

src/main/java/eu/dnetlib/dhp/schema/oaf/H2020Programme.java

@@ -9,8 +9,9 @@ import java.util.Objects;
  * - private String code to store the code of the programme
  * - private String description to store the description of the programme
  */
-
 public class H2020Programme implements Serializable {
+
+	private static final long serialVersionUID = -7851791644568592481L;
 	private String code;
 	private String description;
 

src/main/java/eu/dnetlib/dhp/schema/oaf/Instance.java

@@ -6,6 +6,7 @@ import java.util.List;
 
 public class Instance implements Serializable {
 
+	private static final long serialVersionUID = 3918544870298859300L;
 	private Field<String> license;
 
 	private AccessRight accessright;

src/main/java/eu/dnetlib/dhp/schema/oaf/InstanceTypeMapping.java

@@ -7,6 +7,7 @@ import java.io.Serializable;
  */
 public class InstanceTypeMapping implements Serializable {
 
+    private static final long serialVersionUID = -8209930054790495309L;
     /**
      * Original resource type, typically mapped from dc:type, datacite:resourceType.
      */

src/main/java/eu/dnetlib/dhp/schema/oaf/Journal.java

@@ -6,6 +6,8 @@ import java.util.Objects;
 
 public class Journal implements Serializable {
 
+	private static final long serialVersionUID = -8476321782780781681L;
+
 	private String name;
 
 	private String issnPrinted;

src/main/java/eu/dnetlib/dhp/schema/oaf/KeyValue.java

@@ -9,6 +9,7 @@ import com.fasterxml.jackson.annotation.JsonIgnore;
 
 public class KeyValue implements Serializable {
 
+	private static final long serialVersionUID = 1905267445569591240L;
 	private String key;
 
 	private String value;

src/main/java/eu/dnetlib/dhp/schema/oaf/Measure.java

@@ -11,6 +11,7 @@ import com.google.common.base.Objects;
  */
 public class Measure implements Serializable {
 
+	private static final long serialVersionUID = 8383308453679722661L;
 	/**
 	 * Unique measure identifier.
 	 */

src/main/java/eu/dnetlib/dhp/schema/oaf/OAIProvenance.java

@@ -6,6 +6,8 @@ import java.util.Objects;
 
 public class OAIProvenance implements Serializable {
 
+	private static final long serialVersionUID = -767252660700352729L;
+
 	private OriginDescription originDescription;
 
 	public OriginDescription getOriginDescription() {

src/main/java/eu/dnetlib/dhp/schema/oaf/Oaf.java

@@ -11,6 +11,7 @@ import java.util.stream.Stream;
 
 public abstract class Oaf implements Serializable {
 
+	private static final long serialVersionUID = 94599232915572420L;
 	/**
 	 * The list of datasource id/name pairs providing this relationship.
 	 */

src/main/java/eu/dnetlib/dhp/schema/oaf/OafEntity.java

@@ -7,6 +7,8 @@ import java.util.stream.Collectors;
 
 public abstract class OafEntity extends Oaf implements Serializable {
 
+	private static final long serialVersionUID = -7793594664115821897L;
+
 	private String id;
 
 	private List<String> originalId;

src/main/java/eu/dnetlib/dhp/schema/oaf/OpenAccessColor.java

@@ -1,11 +1,12 @@
 
 package eu.dnetlib.dhp.schema.oaf;
 
+import java.io.Serializable;
+
 /**
  * The OpenAccess color meant to be used on the result level
  */
-public enum OpenAccessColor {
-
+public enum OpenAccessColor implements Serializable {
 	gold, hybrid, bronze
 
 }

src/main/java/eu/dnetlib/dhp/schema/oaf/Organization.java

@@ -6,6 +6,8 @@ import java.util.List;
 
 public class Organization extends OafEntity implements Serializable {
 
+	private static final long serialVersionUID = -9048723860770504113L;
+
 	private Field<String> legalshortname;
 
 	private Field<String> legalname;

src/main/java/eu/dnetlib/dhp/schema/oaf/OriginDescription.java

@@ -6,6 +6,8 @@ import java.util.Objects;
 
 public class OriginDescription implements Serializable {
 
+	private static final long serialVersionUID = -7256156902727658863L;
+
 	private String harvestDate;
 
 	private Boolean altered = true;

src/main/java/eu/dnetlib/dhp/schema/oaf/OtherResearchProduct.java

@@ -8,6 +8,8 @@ import eu.dnetlib.dhp.schema.common.ModelConstants;
 
 public class OtherResearchProduct extends Result implements Serializable {
 
+	private static final long serialVersionUID = -7611546868867175491L;
+
 	private List<Field<String>> contactperson;
 
 	private List<Field<String>> contactgroup;

src/main/java/eu/dnetlib/dhp/schema/oaf/Project.java

@@ -8,6 +8,8 @@ import org.apache.commons.lang3.StringUtils;
 
 public class Project extends OafEntity implements Serializable {
 
+	private static final long serialVersionUID = 5783959097903529424L;
+
 	private Field<String> websiteurl;
 
 	private Field<String> code;

src/main/java/eu/dnetlib/dhp/schema/oaf/Publication.java

@@ -7,6 +7,8 @@ import eu.dnetlib.dhp.schema.common.ModelConstants;
 
 public class Publication extends Result implements Serializable {
 
+	private static final long serialVersionUID = 4155353046627214846L;
+
 	// publication specific
 	private Journal journal;
 

src/main/java/eu/dnetlib/dhp/schema/oaf/Qualifier.java

@@ -8,7 +8,7 @@ import org.apache.commons.lang3.StringUtils;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 
 public class Qualifier implements Serializable {
-
+	private static final long serialVersionUID = 6632548656644563076L;
 	private String classid;
 	private String classname;
 	private String schemeid;

src/main/java/eu/dnetlib/dhp/schema/oaf/Relation.java

@@ -18,6 +18,8 @@ import eu.dnetlib.dhp.schema.common.ModelSupport;
  */
 public class Relation extends Oaf {
 
+	private static final long serialVersionUID = -7061565324218172207L;
+
 	/**
 	 * Main relationship classifier, values include 'resultResult', 'resultProject', 'resultOrganization', etc.
 	 */

src/main/java/eu/dnetlib/dhp/schema/oaf/Result.java

@@ -23,6 +23,8 @@ import eu.dnetlib.dhp.schema.oaf.utils.CleaningFunctions;
  */
 public class Result extends OafEntity implements Serializable {
 
+	private static final long serialVersionUID = 5597290552671699408L;
+
 	/**
 	 * ( article | book ) processing charges.
  	 */

src/main/java/eu/dnetlib/dhp/schema/oaf/Software.java

@@ -8,6 +8,8 @@ import eu.dnetlib.dhp.schema.common.ModelConstants;
 
 public class Software extends Result implements Serializable {
 
+	private static final long serialVersionUID = -3096641763359312576L;
+
 	private List<Field<String>> documentationUrl;
 
 	// candidate for removal

src/main/java/eu/dnetlib/dhp/schema/oaf/StructuredProperty.java

@@ -10,6 +10,8 @@ import org.apache.commons.lang3.StringUtils;
 
 public class StructuredProperty implements Serializable {
 
+	private static final long serialVersionUID = -8490243153237377762L;
+
 	private String value;
 
 	private Qualifier qualifier;

src/main/java/eu/dnetlib/dhp/schema/oaf/Subject.java

@@ -3,4 +3,7 @@ package eu.dnetlib.dhp.schema.oaf;
 import java.io.Serializable;
 
 public class Subject extends StructuredProperty implements Serializable {
+
+    private static final long serialVersionUID = 5072481219939207428L;
+
 }

src/main/java/eu/dnetlib/dhp/schema/solr/APC.java

@@ -7,9 +7,12 @@ import java.io.Serializable;
  * currency of type String to store the currency of the APC - amount of type String to stores the charged amount
  */
 public class APC implements Serializable {
-    private String currency;
-    private String amount;
 
+    private static final long serialVersionUID = 8324447899738993669L;
+
+    private String currency;
+
+    private String amount;
 
     public static APC newInstance(String currency, String amount) {
         APC apc = new APC();

src/main/java/eu/dnetlib/dhp/schema/solr/AccessRight.java

@@ -1,12 +1,14 @@
 
 package eu.dnetlib.dhp.schema.solr;
 
-import java.util.Optional;
+import java.io.Serializable;
 
 /**
  * This class models the access rights of research products.
  */
-public class AccessRight {
+public class AccessRight implements Serializable {
+
+	private static final long serialVersionUID = 7995566912611238604L;
 
 	private String value;
 

src/main/java/eu/dnetlib/dhp/schema/solr/Author.java

@@ -5,6 +5,8 @@ import java.util.List;
 
 public class Author implements Serializable {
 
+    private static final long serialVersionUID = 5482727671039062564L;
+
     private String fullname;
 
     private String name;

src/main/java/eu/dnetlib/dhp/schema/solr/BestAccessRight.java

@@ -7,6 +7,8 @@ import java.io.Serializable;
  */
 public class BestAccessRight implements Serializable {
 
+    private static final long serialVersionUID = 689431927147731065L;
+
     /**
      * AccessRight code
      */

src/main/java/eu/dnetlib/dhp/schema/solr/Category.java

@@ -3,11 +3,13 @@ package eu.dnetlib.dhp.schema.solr;
 import java.io.Serializable;
 import java.util.List;
 
+import com.google.common.collect.Lists;
+
 public class Category implements Serializable {
 
     private String id;
     private String label;
-    private List<Concept> concept;
+    private List<Concept> concept = Lists.newArrayList();
 
     public static Category newInstance(String id, String label) {
         Category category = new Category();

src/main/java/eu/dnetlib/dhp/schema/solr/CodeLabel.java

@@ -4,6 +4,8 @@ import java.io.Serializable;
 
 public class CodeLabel implements Serializable {
 
+    private static final long serialVersionUID = 8182033641583483845L;
+
     private String code;
 
     private String label;

src/main/java/eu/dnetlib/dhp/schema/solr/Concept.java

@@ -4,6 +4,8 @@ import java.io.Serializable;
 
 public class Concept implements Serializable {
 
+    private static final long serialVersionUID = -2309379406128410374L;
+
     private String id;
     private String label;
 

src/main/java/eu/dnetlib/dhp/schema/solr/Context.java

@@ -3,12 +3,14 @@ package eu.dnetlib.dhp.schema.solr;
 import java.io.Serializable;
 import java.util.List;
 
+import com.google.common.collect.Lists;
+
 public class Context implements Serializable {
 
     private String id;
     private String label;
     private String type;
-    private List<Category> category;
+    private List<Category> category = Lists.newArrayList();
 
     public static Context newInstance(String id, String label, String type, List<Category> category) {
         Context context = new Context();

src/main/java/eu/dnetlib/dhp/schema/solr/Country.java

@@ -11,6 +11,8 @@ import java.io.Serializable;
  */
 public class Country implements Serializable {
 
+    private static final long serialVersionUID = 544249673120027949L;
+
     /**
      * ISO 3166-1 alpha-2 country code (i.e. IT)
      */

src/main/java/eu/dnetlib/dhp/schema/solr/Datasource.java

@@ -5,6 +5,7 @@ import java.util.List;
 
 public class Datasource implements Serializable {
 
+    private static final long serialVersionUID = -5817484869244344681L;
     private CodeLabel datasourcetype;
 
     private CodeLabel datasourcetypeui;

src/main/java/eu/dnetlib/dhp/schema/solr/EoscIfGuidelines.java

@@ -12,6 +12,8 @@ import org.apache.commons.lang3.StringUtils;
  */
 public class EoscIfGuidelines implements Serializable {
 
+    private static final long serialVersionUID = -6460491699309783829L;
+
     /**
      * EOSC-IF local code. Later on it could be populated with a PID (e.g. DOI), but for the time being we stick to
      * a more loose definition.

src/main/java/eu/dnetlib/dhp/schema/solr/ExtraInfo.java

@@ -4,5 +4,7 @@ import java.io.Serializable;
 
 public class ExtraInfo implements Serializable {
 
+    private static final long serialVersionUID = -6627854860189757709L;
+
     //TODO define me!
 }

src/main/java/eu/dnetlib/dhp/schema/solr/Funder.java

@@ -5,6 +5,8 @@ import java.util.List;
 
 public class Funder implements Serializable {
 
+    private static final long serialVersionUID = -8008317145200052214L;
+
     private String id;
     private String shortname;
     private String name;

src/main/java/eu/dnetlib/dhp/schema/solr/Funding.java

@@ -4,6 +4,8 @@ import java.io.Serializable;
 
 public class Funding implements Serializable {
 
+    private static final long serialVersionUID = 1811734787904369695L;
+
     private Funder funder;
     private FundingLevel level0;
     private FundingLevel level1;

src/main/java/eu/dnetlib/dhp/schema/solr/FundingLevel.java

@@ -4,6 +4,8 @@ import java.io.Serializable;
 
 public class FundingLevel implements Serializable {
 
+    private static final long serialVersionUID = 8270506546250477574L;
+
     private String id;
 
     private String description;

src/main/java/eu/dnetlib/dhp/schema/solr/Instance.java

@@ -5,6 +5,8 @@ import java.util.List;
 
 public class Instance implements Serializable {
 
+    private static final long serialVersionUID = 7440831757124257169L;
+
     private String license;
 
     private AccessRight accessright;

src/main/java/eu/dnetlib/dhp/schema/solr/Journal.java

@@ -4,6 +4,8 @@ import java.io.Serializable;
 
 public class Journal implements Serializable {
 
+    private static final long serialVersionUID = -103050431178898773L;
+
     /**
      * Name of the journal or conference
      */

src/main/java/eu/dnetlib/dhp/schema/solr/Language.java

@@ -4,6 +4,8 @@ import java.io.Serializable;
 
 public class Language implements Serializable {
 
+    private static final long serialVersionUID = -8308628905005193974L;
+
     /**
      * alpha-3/ISO 639-2 code of the language
      */

src/main/java/eu/dnetlib/dhp/schema/solr/Measure.java

@@ -4,5 +4,7 @@ import java.io.Serializable;
 
 public class Measure implements Serializable {
 
+    private static final long serialVersionUID = 57939927121851504L;
+
     //TODO define me!
 }

src/main/java/eu/dnetlib/dhp/schema/solr/Organization.java

@@ -5,6 +5,8 @@ import java.util.List;
 
 public class Organization implements Serializable {
 
+    private static final long serialVersionUID = -4287924905285274034L;
+
     private String legalshortname;
 
     private String legalname;

src/main/java/eu/dnetlib/dhp/schema/solr/Pid.java

@@ -4,6 +4,8 @@ import java.io.Serializable;
 
 public class Pid implements Serializable {
 
+    private static final long serialVersionUID = -943684282582228545L;
+
     private String type;
 
     private String value;

src/main/java/eu/dnetlib/dhp/schema/solr/Project.java

@@ -5,6 +5,8 @@ import java.util.List;
 
 public class Project implements Serializable {
 
+    private static final long serialVersionUID = -3712733565189222788L;
+
     private String websiteurl;
 
     private String code;

src/main/java/eu/dnetlib/dhp/schema/solr/Provenance.java

@@ -4,6 +4,8 @@ import java.io.Serializable;
 
 public class Provenance implements Serializable {
 
+    private static final long serialVersionUID = -474833313621479191L;
+
     private String dsId;
 
     private String dsName;

src/main/java/eu/dnetlib/dhp/schema/solr/RecordType.java

@@ -0,0 +1,14 @@
+package eu.dnetlib.dhp.schema.solr;
+
+import java.io.Serializable;
+
+public enum RecordType implements Serializable {
+    publication,
+    dataset,
+    otherresearchproduct,
+    software,
+    datasource,
+    organization,
+    project;
+
+}

src/main/java/eu/dnetlib/dhp/schema/solr/RelatedRecord.java

@@ -5,6 +5,8 @@ import java.util.List;
 
 public class RelatedRecord implements Serializable {
 
+    private static final long serialVersionUID = -7251015928787319389L;
+
     private RelatedRecordHeader header;
 
     // common fields

src/main/java/eu/dnetlib/dhp/schema/solr/RelatedRecordHeader.java

@@ -4,15 +4,17 @@ import java.io.Serializable;
 
 public class RelatedRecordHeader implements Serializable {
 
+    private static final long serialVersionUID = -1491635071695452382L;
+
     private String relationType;
 
     private String relationClass;
 
     private String relatedIdentifier;
 
-    private String relatedRecordType;
+    private RecordType relatedRecordType;
 
-    public static RelatedRecordHeader newInstance(String relationType, String relationClass, String relatedIdentifier, String relatedRecordType) {
+    public static RelatedRecordHeader newInstance(String relationType, String relationClass, String relatedIdentifier, RecordType relatedRecordType) {
         RelatedRecordHeader header = new RelatedRecordHeader();
         header.setRelationType(relationType);
         header.setRelationClass(relationClass);
@@ -45,11 +47,11 @@ public class RelatedRecordHeader implements Serializable {
         this.relatedIdentifier = relatedIdentifier;
     }
 
-    public String getRelatedRecordType() {
+    public RecordType getRelatedRecordType() {
         return relatedRecordType;
     }
 
-    public void setRelatedRecordType(String relatedRecordType) {
+    public void setRelatedRecordType(RecordType relatedRecordType) {
         this.relatedRecordType = relatedRecordType;
     }
 }

src/main/java/eu/dnetlib/dhp/schema/solr/Result.java

@@ -7,6 +7,8 @@ import com.fasterxml.jackson.annotation.JsonProperty;
 
 public class Result implements Serializable {
 
+    private static final long serialVersionUID = -9121038426985022737L;
+
     /**
      * Type of the result: one of 'publication', 'dataset', 'software', 'other' (see also https://api.openaire.eu/vocabularies/dnet:result_typologies)
      */

src/main/java/eu/dnetlib/dhp/schema/solr/SolrRecord.java

@@ -5,6 +5,8 @@ import java.util.List;
 
 public class SolrRecord implements Serializable {
 
+    private static final long serialVersionUID = 2852901817696335899L;
+
     private SolrRecordHeader header;
 
     private List<Provenance> collectedfrom;

src/main/java/eu/dnetlib/dhp/schema/solr/SolrRecordHeader.java

@@ -5,6 +5,8 @@ import java.util.List;
 
 public class SolrRecordHeader implements Serializable {
 
+    private static final long serialVersionUID = -6052397109220149426L;
+
     /**
      * The OpenAIRE identifiers for this record
      */
@@ -15,10 +17,13 @@ public class SolrRecordHeader implements Serializable {
      */
     private List<String> originalId;
 
-    public static SolrRecordHeader newInstance(String id, List<String> originalId) {
+    private RecordType recordType;
+
+    public static SolrRecordHeader newInstance(String id, List<String> originalId, RecordType recordType) {
         SolrRecordHeader header = new SolrRecordHeader();
         header.setId(id);
         header.setOriginalId(originalId);
+        header.setRecordType(recordType);
         return header;
     }
 
@@ -37,4 +42,12 @@ public class SolrRecordHeader implements Serializable {
     public void setOriginalId(List<String> originalId) {
         this.originalId = originalId;
     }
+
+    public RecordType getRecordType() {
+        return recordType;
+    }
+
+    public void setRecordType(RecordType recordType) {
+        this.recordType = recordType;
+    }
 }

src/main/java/eu/dnetlib/dhp/schema/solr/Subject.java

@@ -4,6 +4,8 @@ import java.io.Serializable;
 
 public class Subject implements Serializable {
 
+    private static final long serialVersionUID = -7242293435544930481L;
+
     private String value;
 
     private String type;