throw IllegalArgumentException if both field name and value are empty (to avoid a confusing "term out of order" exception later)

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@406168 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -13,6 +13,10 @@ API Changes
 
  2. DisjunctionSumScorer is no longer public.
     (Paul Elschot via Otis Gospodnetic)
+    
+ 3. Creating a Field with both an empty name and an empty value 
+    now throws an IllegalArgumentException
+    (Daniel Naber)
 
 Bug fixes
 

src/java/org/apache/lucene/document/Field.java

@@ -238,6 +238,8 @@ public final class Field implements Serializable {
       throw new NullPointerException("name cannot be null");
     if (value == null)
       throw new NullPointerException("value cannot be null");
+    if (name.length() == 0 && value.length() == 0)
+      throw new IllegalArgumentException("name and value cannot both be empty");
     if (index == Index.NO && store == Store.NO)
       throw new IllegalArgumentException("it doesn't make sense to have a field that "
          + "is neither indexed nor stored");