Propertly handle null in StringToCollectionConverter (#19481)

Change-Id: Ief6f899d6c0fec103213c5f679a178555740c553

2 files changed, 22 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();) {
diff --git a/server/tests/src/com/vaadin/tests/data/converter/StringToCollectionConverterTest.java b/server/tests/src/com/vaadin/tests/data/converter/StringToCollectionConverterTest.java
index bcd0dc15bd..4f2dc1df81 100644
--- a/server/tests/src/com/vaadin/tests/data/converter/StringToCollectionConverterTest.java
+++ b/server/tests/src/com/vaadin/tests/data/converter/StringToCollectionConverterTest.java
@@ -22,6 +22,7 @@ import java.util.EnumSet;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
+import java.util.Locale;
 import java.util.Set;
 import java.util.Vector;
 
@@ -151,6 +152,20 @@ public class StringToCollectionConverterTest {
                 iterator.hasNext());
     }
 
+    @Test
+    public void convertToModel_null() {
+        StringToCollectionConverter converter = new StringToCollectionConverter();
+        Assert.assertNull(converter.convertToModel(null, ArrayList.class,
+                Locale.ENGLISH));
+    }
+
+    @Test
+    public void convertToPresentation_null() {
+        StringToCollectionConverter converter = new StringToCollectionConverter();
+        Assert.assertNull(converter.convertToPresentation(null, String.class,
+                Locale.ENGLISH));
+    }
+
     public enum TestEnum {
         X, Y, Z;
     }