Fix MoreLikeThisFullDocumentQueryUsageTests (#3962)

This commit fixes the MoreLikeThisFullDocumentQueryUsageTests. The free text needs fields to target.

Author: russcam

src/Tests/Tests/QueryDsl/Specialized/MoreLikeThis/MoreLikeThisFullDocumentQueryUsageTests.cs

@@ -12,6 +12,9 @@ public MoreLikeThisFullDocumentQueryUsageTests(ReadOnlyCluster i, EndpointUsage
 
 		protected override QueryContainer QueryInitializer => new MoreLikeThisQuery
 		{
+			Fields = Infer.Fields<Project>(
+				f => f.Name,
+				f => f.Description),
 			Like = new List<Like>
 			{
 				new LikeDocument<Project>(Project.Instance) { Routing = Project.Instance.Name },
@@ -23,6 +26,11 @@ public MoreLikeThisFullDocumentQueryUsageTests(ReadOnlyCluster i, EndpointUsage
 		{
 			more_like_this = new
 			{
+				fields = new []
+				{
+					"name",
+					"description"
+				},
 				like = new object[]
 				{
 					new
@@ -38,6 +46,10 @@ public MoreLikeThisFullDocumentQueryUsageTests(ReadOnlyCluster i, EndpointUsage
 
 		protected override QueryContainer QueryFluent(QueryContainerDescriptor<Project> q) => q
 			.MoreLikeThis(sn => sn
+				.Fields(ff => ff
+					.Field(f => f.Name)
+					.Field(f => f.Description)
+				)
 				.Like(l => l
 					.Document(d => d
 						.Document(Project.Instance)