#1643 - ENH: Add expression inOrEmpty() ... as a convenience for conditionally added a IN expression

src/main/java/io/ebeaninternal/server/expression/DefaultExpressionFactory.java

@@ -455,6 +455,16 @@ public class DefaultExpressionFactory implements SpiExpressionFactory {
     return new InExpression(propertyName, values, false);
   }
 
+  /**
+   * In where null or empty values means that no predicate is added to the query.
+   * <p>
+   * That is, only add the IN predicate if the values are not null or empty.
+   */
+  @Override
+  public Expression inOrEmpty(String propertyName, Collection<?> values) {
+    return new InExpression(propertyName, values, false, true);
+  }
+
   /**
    * In - property has a value in the array of values.
    */