Change fetch type from EAGER to LAZY, as it is otherwise crippling performance...

Change fetch type from EAGER to LAZY, as it is otherwise crippling performance for big BundlesSources during org.gesis.dda.wizard.service.FeederService.createOrUpdateBundle(..) (see org.hibernate.SQL log on DEBUG level)

src/main/java/org/gesis/dda/wizard/domain/Bundle.java

 package org.gesis.dda.wizard.domain;
 
-import com.fasterxml.jackson.annotation.JsonIgnore;
-import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import java.io.Serializable;
+import java.time.Instant;
+import java.util.Objects;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import javax.persistence.CollectionTable;
+import javax.persistence.Column;
+import javax.persistence.ElementCollection;
+import javax.persistence.Entity;
+import javax.persistence.EnumType;
+import javax.persistence.Enumerated;
+import javax.persistence.FetchType;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.JoinColumn;
+import javax.persistence.ManyToOne;
+import javax.persistence.Table;
+
 import org.gesis.dda.publishing.domain.Metadatum;
 import org.gesis.dda.publishing.domain.impl.JpaMetadatum;
 import org.gesis.dda.wizard.domain.enumeration.BundleState;
@@ -9,12 +27,8 @@ import org.gesis.dda.wizard.service.BundleService;
 import org.hibernate.annotations.Cache;
 import org.hibernate.annotations.CacheConcurrencyStrategy;
 
-import javax.persistence.*;
-import java.io.Serializable;
-import java.time.Instant;
-import java.util.Objects;
-import java.util.Set;
-import java.util.stream.Collectors;
+import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
 
 /**
  * A Bundle.
@@ -45,7 +59,7 @@ public class Bundle implements Serializable, org.gesis.dda.publishing.domain.Bun
     @Column(name = "last_harvesting_instant")
     private Instant lastHarvestingInstant;
 
-    @ElementCollection(fetch = FetchType.EAGER)
+    @ElementCollection(fetch = FetchType.LAZY)
     @CollectionTable(name="metadatum",
                      joinColumns=@JoinColumn(name="bundle_id")
     )
@@ -59,6 +73,7 @@ public class Bundle implements Serializable, org.gesis.dda.publishing.domain.Bun
         this.id = id;
     }
 
+    @Override
     public String getReference() {
         return reference;
     }