[DS-2763] Continue cleaning up serialization bugs found by Findbugs

dspace-api/src/main/java/org/dspace/content/CollectionNameComparator.java

@@ -7,9 +7,15 @@
  */
 package org.dspace.content;
 
+import java.io.Serializable;
 import java.util.Comparator;
 
-public class CollectionNameComparator implements Comparator<Collection> {
+/**
+ * Compares the names of two {@link Collection}s.
+ */
+public class CollectionNameComparator
+        implements Comparator<Collection>, Serializable
+{
     @Override
     public int compare(Collection collection1, Collection collection2) {
         return collection1.getName().compareTo(collection2.getName());

dspace-api/src/main/java/org/dspace/content/ItemComparator.java

@@ -40,7 +40,8 @@ public class ItemComparator implements Comparator, Serializable
     /** Whether maximum or minimum value will be used */
     protected boolean max;
 
-    protected ItemService itemService;
+    protected transient ItemService itemService
+            = ContentServiceFactory.getInstance().getItemService();
 
     /**
      * Constructor.
@@ -63,7 +64,6 @@ public class ItemComparator implements Comparator, Serializable
         this.qualifier = qualifier;
         this.language = language;
         this.max = max;
-        this.itemService = ContentServiceFactory.getInstance().getItemService();
     }
 
     /**
@@ -127,6 +127,7 @@ public class ItemComparator implements Comparator, Serializable
      *            The object to compare to.
      * @return True if the other object is equal to this one, false otherwise.
      */
+    @Override
     public boolean equals(Object obj)
     {
         if (!(obj instanceof ItemComparator))
@@ -141,13 +142,16 @@ public class ItemComparator implements Comparator, Serializable
                 && equalsWithNull(language, other.language) && (max == other.max);
     }
 
+    @Override
     public int hashCode()
     {
         return new HashCodeBuilder().append(element).append(qualifier).append(language).append(max).toHashCode();
     }
 
     /**
-     * Return true if the first string is equal to the second. Either or both
+     * @param first
+     * @param second
+     * @return true if the first string is equal to the second. Either or both
      * may be null.
      */
     protected boolean equalsWithNull(String first, String second)
@@ -180,7 +184,7 @@ public class ItemComparator implements Comparator, Serializable
         // The overall array and each element are guaranteed non-null
         List<MetadataValue> dcvalues = itemService.getMetadata(item, MetadataSchema.DC_SCHEMA, element, qualifier, language);
 
-        if (dcvalues.size() == 0)
+        if (dcvalues.isEmpty())
         {
             return null;
         }
@@ -192,7 +196,7 @@ public class ItemComparator implements Comparator, Serializable
 
         // We want to sort using Strings, but also keep track of
         // which Metadatum the value came from.
-        Map<String, Integer> values = new HashMap<String, Integer>();
+        Map<String, Integer> values = new HashMap<>();
 
         for (int i = 0; i < dcvalues.size(); i++)
         {
@@ -204,7 +208,7 @@ public class ItemComparator implements Comparator, Serializable
             }
         }
 
-        if (values.size() == 0)
+        if (values.isEmpty())
         {
             return null;
         }
@@ -220,6 +224,8 @@ public class ItemComparator implements Comparator, Serializable
 
     /**
      * Normalize the title of a Metadatum.
+     * @param value
+     * @return
      */
     protected String normalizeTitle(MetadataValue value)
     {

dspace-api/src/main/java/org/dspace/content/dao/DSpaceObjectDAO.java

@@ -15,6 +15,7 @@ import org.dspace.core.GenericDAO;
  * All DSpaceObject DAO classes should implement this class since it ensures that the T object is of type DSpaceObject
  *
  * @author kevinvandevelde at atmire.com
+ * @param <T>
  */
 public interface DSpaceObjectDAO<T extends DSpaceObject> extends GenericDAO<T> {
 }

dspace-api/src/main/java/org/dspace/content/dao/DSpaceObjectLegacySupportDAO.java

@@ -17,6 +17,7 @@ import java.sql.SQLException;
  * to identify DSpaceObjects prior to DSpace 6.0
  *
  * @author kevinvandevelde at atmire.com
+ * @param <T>
  */
 public interface DSpaceObjectLegacySupportDAO<T extends DSpaceObject> extends DSpaceObjectDAO<T> {