60823: DGET function, correct behavior with multiple result entries but only one non-blank

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1787658 13f79535-47bb-0310-9956-ffa450edef68

src/java/org/apache/poi/ss/formula/functions/DGet.java

@@ -36,11 +36,19 @@ public final class DGet implements IDStarAlgorithm {
         {
             result = eval;
         }
-        else // There was a previous match, since there is only exactly one allowed, bail out.
+        else // There was a previous match. Only one non-blank result is allowed. #NUM! on multiple values.
         {
+            if(result instanceof BlankEval) {
+                result = eval;
+            }
+            else {
+                // We have a previous filled result.
+                if(!(eval instanceof BlankEval)) {
                     result = ErrorEval.NUM_ERROR;
                     return false;
                 }
+            }
+        }
 
         return true;
     }