Propertly handle null in StringToCollectionConverter (#19481)

Change-Id: Ief6f899d6c0fec103213c5f679a178555740c553

1 files changed, 7 insertions, 0 deletions

diff --git a/server/src/com/vaadin/data/util/converter/StringToCollectionConverter.java b/server/src/com/vaadin/data/util/converter/StringToCollectionConverter.java
index b86fec5558..6930b6da06 100644
--- a/server/src/com/vaadin/data/util/converter/StringToCollectionConverter.java
+++ b/server/src/com/vaadin/data/util/converter/StringToCollectionConverter.java
@@ -145,6 +145,10 @@ public class StringToCollectionConverter implements
     public Collection convertToModel(String value,
             Class<? extends Collection> targetType, Locale locale)
             throws Converter.ConversionException {
+        if (value == null) {
+            return null;
+        }
+
         int index = value.indexOf(delimiter);
         int previous = 0;
         Collection result = factory.createCollection(targetType);
@@ -163,6 +167,9 @@ public class StringToCollectionConverter implements
     public String convertToPresentation(Collection value,
             Class<? extends String> targetType, Locale locale)
             throws Converter.ConversionException {
+        if (value == null) {
+            return null;
+        }
         StringBuilder builder = new StringBuilder();
         Converter converter = tokenConverter;
         for (Iterator<?> iterator = value.iterator(); iterator.hasNext();) {