DOC: more source docs

src/main/java/org/caosdb/server/entity/UpdateEntity.java

@@ -22,11 +22,19 @@
  */
 package org.caosdb.server.entity;
 
+import org.caosdb.server.transaction.Update;
 import org.caosdb.server.utils.EntityStatus;
 import org.jdom2.Element;
 
+/**
+ * UpdateEntity class represents entities which are to be updated. The previous version is appeded
+ * during the {@link Update} transactions initialization.
+ *
+ * @author Timm Fitschen (t.fitschen@indiscale.com)
+ */
 public class UpdateEntity extends WritableEntity {
 
+  /** The previous version of this entity. */
   private EntityInterface original = null;
 
   public UpdateEntity(final Element element) {