add replace subfield method to MarcField builder

gradle.properties

@@ -1,5 +1,5 @@
 group = org.xbib
 name = marc
-version = 2.11.0
+version = 2.12.0
 
 org.gradle.warning.mode = ALL

src/main/java/org/xbib/marc/MarcField.java

@@ -15,6 +15,7 @@
  */
 package org.xbib.marc;
 
+import java.util.Objects;
 import org.xbib.marc.dialects.mab.MabSubfieldControl;
 import org.xbib.marc.label.RecordLabel;
 
@@ -609,6 +610,7 @@ public class MarcField implements Comparable<MarcField> {
          * @return this builder
          */
         public Builder removeSubfields(Set<String> subfieldIds) {
+            // create a new subfield list and replace the whole list by a filtered list
             LinkedList<Subfield> list = subfields.stream()
                     .filter(sf -> !subfieldIds.contains(sf.id))
                     .collect(Collectors.toCollection(LinkedList::new));
@@ -617,6 +619,22 @@ public class MarcField implements Comparable<MarcField> {
             return this;
         }
 
+        /**
+         * In-place replacement of all subfields with a given ID.
+         * @param subfieldId the subfield ID
+         * @param newValue the new value, must be non-null
+         * @return this builder
+         */
+        public Builder replace(String subfieldId, String newValue) {
+            Objects.requireNonNull(newValue);
+            for (Subfield subfield : subfields) {
+                if (subfield.getId().equals(subfieldId)) {
+                    subfield.setValue(newValue);
+                }
+            }
+            return this;
+        }
+
         /**
          * Copy a MARC field into this builder.
          * @param field the MARC field to copy
@@ -785,7 +803,7 @@ public class MarcField implements Comparable<MarcField> {
 
         private final String id;
 
-        private final String value;
+        private String value;
 
         private Subfield(String id, String value) {
             this.id = id;
@@ -808,6 +826,10 @@ public class MarcField implements Comparable<MarcField> {
             return value;
         }
 
+        private void setValue(String value) {
+            this.value = value;
+        }
+
         @Override
         public boolean equals(Object obj) {
             return obj instanceof Subfield && toString().equals(obj.toString());