Fix LT-21815: Eliminate empty glosses (#300)

* Add IsEmptyMultiUnicode and add it to the check before merging sense glosses into the word gloss
* Remove the default word gloss content if no sense gloss content was merged

---------

Co-authored-by: Jason Naylor <jasonleenaylor@users.noreply.github.com>

src/SIL.LCModel/DomainServices/AnalysisGuessServices.cs

@@ -1032,12 +1032,17 @@ private void GenerateEntryGuesses(IDictionary<IWfiWordform, EmptyWwfInfo> map)
 							var newAnalysis = waFactory.Create(ww, wgFactory);
 							newAnalysis.CategoryRA = info.Pos;
 							// Not all entries have senses.
-							if (info.Sense != null)
+							if (info.Sense != null && !IsEmptyMultiUnicode(info.Sense.Gloss))
 							{
 								// copy all the gloss alternatives from the sense into the word gloss.
 								IWfiGloss wg = newAnalysis.MeaningsOC.First();
 								wg.Form.MergeAlternatives(info.Sense.Gloss);
 							}
+							else
+							{
+								// Eliminate the dummy gloss (LT-21815).
+								newAnalysis.MeaningsOC.Clear();
+							}
 							var wmb = wmbFactory.Create();
 							newAnalysis.MorphBundlesOS.Add(wmb);
 							if (info.Form != null)
@@ -1058,6 +1063,16 @@ private void GenerateEntryGuesses(IDictionary<IWfiWordform, EmptyWwfInfo> map)
 				}
 			}
 		}
+
+		bool IsEmptyMultiUnicode(IMultiUnicode multiUnicode)
+		{
+			foreach (var ws in multiUnicode.AvailableWritingSystemIds)
+			{
+				if (multiUnicode.get_String(ws).Length > 0)
+					return false;
+			}
+			return true;
+		}
 		#endregion GenerateEntryGuesses
 	}
 }