Return an empty collection instead of null from Validatable.getValidators() (#9723)

2 files changed, 9 insertions, 7 deletions

diff --git a/server/src/com/vaadin/data/Validatable.java b/server/src/com/vaadin/data/Validatable.java
index a454e6f821..724a688efb 100644
--- a/server/src/com/vaadin/data/Validatable.java
+++ b/server/src/com/vaadin/data/Validatable.java
@@ -59,11 +59,12 @@ public interface Validatable extends Serializable {
 
     /**
      * <p>
-     * Lists all validators currently registered for the object. If no
-     * validators are registered, returns <code>null</code>.
+     * Returns a collection of all validators currently registered for the
+     * object. The collection may be immutable and it may not be safe to call
+     * <code>removeValidator</code> for this object while iterating over it.
      * </p>
      * 
-     * @return collection of validators or <code>null</code>
+     * @return A collection of validators
      */
     public Collection<Validator> getValidators();
 
diff --git a/server/src/com/vaadin/ui/AbstractField.java b/server/src/com/vaadin/ui/AbstractField.java
index e7d6d9a4ec..7fc5252eee 100644
--- a/server/src/com/vaadin/ui/AbstractField.java
+++ b/server/src/com/vaadin/ui/AbstractField.java
@@ -776,15 +776,16 @@ public abstract class AbstractField<T> extends AbstractComponent implements
     /**
      * Gets the validators of the field.
      * 
-     * @return the Unmodifiable collection that holds all validators for the
+     * @return An unmodifiable collection that holds all validators for the
      *         field.
      */
     @Override
     public Collection<Validator> getValidators() {
-        if (validators == null || validators.isEmpty()) {
-            return null;
+        if (validators == null) {
+            return Collections.emptyList();
+        } else {
+            return Collections.unmodifiableCollection(validators);
         }
-        return Collections.unmodifiableCollection(validators);
     }
 
     /**